Drivers Door Lock

my drivers door lock started playing up earlier this year, the car was still under warranty at the time so i put it into the garage, where they put a new control box in the door (i think!!)

Now it's started playing up again and they don't want to know because the car is out of warranty even though it is less than 12 months since genuine parts fitted.

i now have to lock the car with the key as the remote will only lock the boot and other doors. Has anyone come accross a problem like this before?? any ideas what it could be and how to fix it as it's a proper pain!!

Thanks Stu