Remote Car Starter Installed

$400 for a remote starter that caused $300 worth of damage to my car due to faulty installation . And Doc's says it's my problem. Very Dissatisfied! I recently had a problem with my cars security system and the dealership discovered it was due to improper splicing of wires into the cars security wiring that was done by Doc's Radio & TV. I took the dealers repair report to Doc's and their reply was. "If the remote starter still works... then it is not our problem" I said yes but it caused other things not to work. They said "we are constantly getting people coming back here saying that their dealership is saying their car troubles are because of something we installed". ( Hummm no red flags there) I said well I have it all documented in writing. They said you and everyone else. I asked if maybe they could give me a gift card for future service at their store and they flatly refused. I again asked for a credit in some form even if it was only for half , or a just a portion of my repair bill and they said NO! Their customer service is great until you have a problem...then it is non- existent.