BWM 1 series not locking ?

i have a 1 series, 2005. It has randomly and suddenly stopped locking with the key fob. in the first instance it wasn't locking with the key, and if i manually put the key into the door to open it, the alarm would go off. the alarm then started to go off randomly and stop going off itself too. random symbols appeared on the dashboard. I took it to the specialist garage and they fixed everything but the locks. they installed a new fuse unit, thinking it was wiring that was at fault. the key still wouldnt open/lock the doors when i pressed it. i then took it to another specialist garage and I have had the key reprogrammed, a new ecu chip installed in the car which is behind the dashboard (forgive my ignorance with the parts), the car has been with them for 2 weeks and they are baffled. this is the second specialist garage that cant find out what the problem is. I just want to know what the problem is as specialists cannot even diagnose it now! thank you