Hatchback latch changeout

2010 Nisan Versa. Latch quite working. Shop suggested a new latch assembly. $300 later. Latch still does not work. No one seemed to have anything to suggest except that it is probably the add-on security system that was causing the problem. I was stunned that this was their only suggestion as this problem is not unique to me. One only has to go on the internet to see that it is certainly is not uncommon problem with Nissan hatchbacks. The security system was put in two years ago and the hatch problem started less than 3 months ago. I'm guessing that the local shop has no clue what they are doing when it comes to this electronic and computer problem. I did stop at the place that put the after-purchase equipment on the car and talk to them but I don't, for a minute believe that their product is the problem. Do you think that I will return to this shop in the near future?