Dude, that's bullsh!t. I'd go in there and tell him straight up, I know you're trying to fvck me over, either replace my subs and do it the right way, or I can take you to court for not fulfilling what I paid for. You paid for IDQ's to be installed right, not JLW0's he's trying to MAKE you buy by pulling this crap. He is trying to give you that crap so you'll come back later and try to upgrade, is my guess. Go in there with a no-nonsense attitude. Fight for what you paid for and didn't recieve. Tell them they're the crappiest, caraudio-illiterate bastards, and you'll never come back again, and you'll tell everyone you know. They should by then drop their shit and do what they should have done the first time.
Don't let this a@shole take your money and make you settle for less.
PS: Spend some more time here and learn on installing audio things yourself. You will be much more satisfied, and will cost alot less. Just a suggestion man, I don't wanna see this happen to you again, and I hope you get what you payed for!