Hmm, well lets hope you get it sorted. Still i don't really see how they can fix the slide thing as it seems like the back is all worn, in which case they would have to replace that part of the phone which seems to me being pointless as you might as well just get a new one, oh well when will they learn .
f you get the same one back and it is faulty make sure you get a new one and make a BIG fuss.