Remote Car Starter Defective / Install and Uninstall Fees

Hoping to get some advice. We won a decent remote car starter and went to get it installed by a reputable technician. He was charging $300 for install plus $100 for an analog interface part (might have the terminology wrong). After install get discovered starter was defective and uninstalled. Now option is to pay over $600 for install, uninstall and the part they say is no good to them. Or pay an extra $350 for a new part and starter. Is this fair? My wife paid $960 already despite them not installing the new starter so I need to decide if this is fair and go ahead or if I want the difference back (if I can get it he has our money already with no real invoice). Never really wanted a car starter in the first place so not too fussed about getting one. This is for an Acura 2011 RDX and a after market remote starter.