I cant see them fighting you too hard fella, however it is a really, really easy mistake to make, once the wheel is out of your bike if they don't mark the tyre up for chain/drive side when fitting the new tyre they are in the dark, simple checks will stop it from happening but ultimately time will possibly be the deciding factor, when correcting the cock up if it was recently done and there are no punctures etc that would require you to remove the tyre once more then it would seem unreasonable for them not to hold their hands up.
