I know how it all sounds at 1st, I was SUPER skeptical ; ) But I bought one for £22 on Saturday night and I received the code on Sunday morning and redeemed it through itunes and have been happily purchasing TONs of music ever since. Since I almost run out of my initial £100, (greedy I know ;) I decided to buy another one on Sunday afternoon. Got it two hours later!!!
The seller is prompt, friendly and you can contact him (just don;`t overload his inbox, he must have mountains of emails already!)
for £7 / £5 off input the discount code MSE when you click buy.
(I`ve gotten £200 worth of potential music for £42, awesome! btw the credits valid for 2 years, just redeem it quick though, as the codes only valid for 2 months apparently (so not that quick ;)))