I'd keep complaining and say your not paying the 25% for something that involves putting it back in a warehouse which you could probably do if you were there.
You even said you'd be willing to pay to send it back and they are issuing a restocking fee you're right they are taking the piss. Best bet is probably to ring them up and be firm but civil with them.
Emailing is easy for them to fob you off but when they have to deal with someone on the phone and hear the pissed off voice they might respond differently.
Bloody 25% restocking fee for untouched goods f***ing having a laugh! I would actually tell them they're taking the mick on the phone and being very unreasonable, already putting you out of pocket more so. Should even say their badly designed site was responsible... infact show me the site I'm a designer I wanna have a look at this poor design so I can nit pick it
