It may help you out a bit mate but if 'they' cocked up on what they sent you (i.e. wasn't what you asked for or as described/photographed on the net) then THEY not YOU have to pay for all the postage you paid.
Try looking at the Sale of Goods Act and, in particular, 'distance selling' which will confirm what I've said. If they wont pay it then you can a) take them to the Financial Ombudsman or b) take them to small claims where you'll get your money and your costs back.
I'd say normally for a few quid it's not worth it but when people are being complete arseholes (service wise) I always sort 'em out...only way they learn.
Had problems with Turd Power myself....bought one thing and would never use them again...useless isn't the word.
Hope that helps
Dave