There is a seller who is advertising bass gear for sale (eg. SansAmp pedals on Facebook) and failing to deliver them.
They look to get you to pay by bank transfer or PayPal Gift/Friends & Family.
(TIP: learn from other people's mistakes and don't agree to pay by an unsecured method!)
After receiving payment the seller will promise to send the item, possibly via their daughter.
You won't receive the item and after a time to allow it to come through, you'll get back to the seller to ask them about it and (after a few more days delay) they'll respond that the postal service messed up and returned it to them.
(NOTE: At this point they have confirmed that they have both your item and your money.)
They may give you tracking information; read it carefully and check that it shows a failed delivery attempt to you.
(NOTE: We have people who have been given the SAME tracking ID as proof of the "failed delivery".)
They may offer to re-send it. If you agree to that, start again from the beginning.
(TIP: Learn from other people's mistakes and don't agree to that!)
So, you request a refund. They get back to you and ask for your bank details or PayPal, which you give them and they promise to refund you after work.
You check next day and there's no refund, so you ask for an update; if you gave them bank details, they may ask for PayPal. Repeat this several times until you begin to wonder if something is not quite right.
You then start to do some online checks and the penny drops that you're not the first person who has gone through this. Oh dear, you're being scammed...
Your searches may have even turned up a caravan fraud conviction. If you message the seller that you know about this, they may come back and say they took the rap for a dying friend. Whether or not this is true is irrelevant; the point to note is that their claim to make you trust them is that they lied in a court of law and they prevented the actual scammer from being brought to justice.
(LINK: https://www.leicestermercury.co.uk/news/local-news/single-mum-pensioners-ingoldmells-caravan-3743529)
You then message the seller with a more strident request for your money back and an escalation occurs; they will try and take control of the process and tell you to either "do one", or start saying "do you know who I am?".
From this point on, be very careful to plainly, calmly, and politely insist that you want your money back; do not respond in kind to their escalation.
If you have chosen to post messages in fora or Facebook groups. You may find that the seller will demand you take them down before they will refund you and may escalate matters further, posting abuse and insults, telling you they will get you removed from Facebook groups who their friends run, threatening to sue you, saying they want to come to your house and sorting it out face-to face.
(TIP: Make sure that what you post is true and could not be interpreted as threats or lies, so be sure that they are factually correct statements; there is no point in posting speculation about possible outcomes, the evolutionary maturity of the seller, and suchlike.)
Do not respond in kind, but keep insisting they refund you.
(TIP: If they do try and intimidate or threaten you, for example saying they want to come to your house and sort it out face-to-face, do not agree, but instead call your local Police and tell them - they may say call 999 if they do turn up.)
You've now got to the point where you realise that they are not intending to refund you and would prefer you to just meekly go away.
Raise a case with Action Fraud (https://www.actionfraud.police.uk/) detailing the transaction and payment (they have several such cases already logged) and contact your bank's fraud department (if bank transfer). Inform the seller. They may respond with a derisory comment and more threats, etc. They may even try to dig up some dirt, or make false accusations against you to try and frighten you, and will again say they're going to sue you; they have tried this tactic on many of their victims.
(TIP: If you found the caravan fraud article, you will see that they are a convicted fraudster and used similar techniques in fobbing off their victims then.)
It will at this point likely be a month or more after you initially paid for the item which you haven't received.
You may be contacted by an intermediary or proxy who will offer to help get it sorted. They will also try and get you to remove your posts, reiterate how bad it would be for you if the seller decided to sue you, and so-on. Humour this person, as they may help get your money returned. But do not agree to any conditions regarding taking any of your posts down; the rightful refund of your money is not conditional.
If the refund is still not forthcoming, the next step is to register a case with Money Claim Online (https://www.gov.uk/make-money-claim); there is a £25 fee associated with this, but it will be added to the seller's debt, and you can also add daily interest on the amount (from the date of payment).
It may be the case that they agree to refund before that; if so, it will feel like a small victory, but the reality is that you have got back to the position you were in before the start of the whole sorry process.
If they do not refund you at this point, then they are facing the fraud action you have raised, for which there will be plenty of corroborating evidence, and a CCJ (County Court Judgment) and further debt resulting from the Money Claim Online proceedings.
Once you do get your money back, consider leaving your posts up to help warn others.
(NOTE: You have not entered into any "gentleman's" agreement with the fraudster and are not held by any code they think they have imposed on you.)
(TIP: If you need advice, feel free to ask, either in the thread itself, which is publicly viewable, or by messaging members)
Relevant links:
https://www.actionfraud.police.uk/
https://www.gov.uk/make-money-claim
https://www.leicestermercury.co.uk/news/local-news/single-mum-pensioners-ingoldmells-caravan-3743529
https://www.linkedin.com/in/mick-mason-344b21104/?originalSubdomain=uk
https://www.facebook.com/everythingchangesshow/
https://twitter.com/FunktionJ
https://www.funktionjunction.com/
https://www.facebook.com/thecarpentersexperience/