Removing the relay was a nightmare and impossible for me, I even put on a rubber high-grip glove (for holding glass) and still could not get it to budge.
After a bit of head scratching, I found that I was able to remove
just the top part of the boot lining by gently pulling it out. This gave me enough angle on the bolts that hold the peice of metal onto the bodywork to which the relay is attached. Once those bolts are removed you can get the relay into a position where you can easily remove it.
Hopefully the pictures will work.
I used the BMW alternative relay, the part number set out at the top of this thread.
Here's the new one installed
and here is the old one...
Hope this helps someone in the future!
R