morally you should let it go, hard to say really, you say it owes you £300, but you were never likely to get anywhere near that figure back, on a great day you would only get £50 i think! stereo gear is like computer gear, 3 months old and its obsolete and lost 50% of its value, so a few years old its pretty much worthless only holds personal value!

id just let it go tbh mate