Thanks for that advice, Andy.  I have decided that turning up at Curry's with the DVD player shoved in my rucksack might lead the staff to suspect that I have somehow mistreated it.  Furthermore, if they do change it for a new one, I won't be able to get it in my rucksack without taking it out of the box and shoving it into my rucksack, which may well damage it.  On balance, therefore, I have decided to wait until my car is available and then I can drive in a civilised manner with my DVD and give the staff WHAT FOR! :P