No it's not reasonable. If the OP had screwed it up himself, there is no reason in the world for him to refuse the shop's original offer to service it again for free. What would he have gained with a cash refund?
Unless you want to go for the conspiracy option, in which the evil OP tries to take down the LDS for reasons known only to himself. So all he needs to do is sabotage the reg, get one of his buddies to film him when it failed, and know in advance that the shop would refuse to offer a cash refund on the service so he could come to Scubaboard and complain about it.