Hi Mozz,
There's 3 micro switches housed in the drivers door lock mechanism. It could be any one of them. A quick dismantle/clean/service usually does the trick 50% of the time, & the other 50% there's evidence of door lock failure.
The fact that the becm has been sent off, & the fact when it was refitted everything was normal except the keyfobs & you've been running for nearly two months points me directly at two possible issues.
The first is, These becm's are a complex piece of kit. A few people have the software to read & program, & advertise as becm repairers, when in fact, they are just programmers. If the becm has a sinister problem & this in turn places the becm into an alarmed state, ie: Keycode Lockout, & by getting the becm reset allowing the car to unlock & start doesn't mean the problem has been fixed. When the becm enters the alarmed state of Keycode Lockout, this is an action resulting from a primary problem.
Data will get corrupted. A serious problem will corrupt & deactivate the EKA code, & one in three will lose the fob code, Hence the fobs not working.
These codes can be replaced & the becm reset, but the primary problem will still exist. Reverse engineering the fault to reveal the problem is where the experiance knowledge & skill are needed so when the becm is returned the integrity of that becm is 100%.
I brought this up a few months back after that huge post with the other chap who was supplied a becm that didn't work.....
That becm can be sent off to be reset umpteen times & it will still go into an alarmed state, deactivating the EKA code all the time the primary problem exists.
Moving onto the door lock & this is where it can start to get expensive, keeping in mind the becm has been done & paid for, & the only way to be 100% certain is to replace the door lock mechanism with a known working one or new. If that's not the problem then it's back to the becm i'm afraid.
Has anyone looked at the under bonnet fusebox?