I have always used Interparcel and never had a problem, despite the wide range of different couriers they work with.
The price is way better than the Post Office (even when it's Parcelforce making the delivery) and you don't need to leave the house - they come to you!
However, I forgot the small print and didn't put a layer of card on the outside of my last parcel. Why? The bass was in a case and so better protected than any cardboard box. I also wrapped it in clingfilm so it wouldn't spring open.
But, this breaches their rules. A fair cop. I had an invoice for ove ten quid as a punishment, with the chance to appeal. I did this explaining that I had secured the instrument in a case and it was a simple mistake.
No dice. Cough up or else.
I'm torn. It was my fault, a clear breach of Ts&Cs so I can have no complaints
On the other hand I had already sold the bass at a 40 quid loss, nor had I charged the full amount for delivery. So another tenner hurts.
I think it's a risky strategy to fine a regular customer for his first mistake though. A warning and 'we're not going to charge you this time' would have endeared me to the company, and deepened my loyalty.
I have stated it was my fault so no need to remind me, I really just want to make sure others don't fall foul of this.