Nothing - it was all diags.

in the end the garage had to do undertake a fresh software update which kick started the module into life once more so no replacement was required.

I'd imagine someone with the right skills and equipment for a pre-2016 car could have done this for free but I wasn't one of them :)

Just glad it did't cost the £400 I was originally fearing.

what sw did they do pdm upgrade probally £24