94M 5dr rhd turbo

A day or two before the MOT/service we noticed the off-side brake light wasn't
working. I tried replacing the bulb but no
joy. I thought about the fuse but the handbook says both brake lights are off the same fuse and the other still works.

As it was going in anyway I mentioned the problem. They say they replaced the bulb and have passed the car, the off-side now works......

On getting the car home (the garage was closed when we picked the car up) we noticed near-side no longer works!

I've replaced the near-side with a bulb that
I know works but still no light. What's going on?