All current NHS aids have two mics. That way, you can have a programme to switch off the rear mic, which helps a little in noisy situations, or when you are sitting next to a hard reflective surface - eg a table near a wal in a restaurant.
The problem is, if you don't know about the different programmes, half the time they don't mention them. Even having the loop setting had to be done second time round for me. Although, bar a few limited situations, loop is pretty useless, as most place have crap loops/dpn't turn them on or don't know how/they are broken.
My HAs drive me nuts. I hate them, and have had some amount of similar exprience to ivansc re the moulds. I finally ended up with moulds which have a cutaway and a tube, rather than the normal two tubes, which helps a bit listening to music. The 'music programme' on the aids is a total joke.
Back to OP: aids out, plugs in.