I replaced 2 of the three key fob batteries while trying to fix the issue (I only had two batteries "in stock") and the dealership have not done anything with the key, so I am confident it unfortunately wasnt the issue (unfortunately as it would have been an easy fix)Thanks for the update. Regards your original problem, it is imperative to replace all fob batteries at 12 month intervals.
In the absence of any further evidence, I believe this is what your issue was. Glad it is now sorted.
I am now just worried about reoccurence after may when the warranty runs out.