[V8 EGO]

Good day everyone. I have a 2011 535d GT and one of my keys has stopped working. The car has comfort access and I have used a variety of different batteries including Panasonic and none work.

We have two keys and the other one works fine. I have taken the key apart and there are no obvious dry joints and I have re-sprung the battery contacts to no avail. The key will not allow the car to be unlocked/locked either remotely or through comfort access and it won't even allow the car to be started when offering up to the steering column.

Has anyone encountered this themselves and how did they sort it? Failing that, does anyone have any recommendations for either key repair or a replacement key in the UK please?