Same issue for me. Ordered the part from Cardiff Audi, arrived next day. Fitted in a few mins and all sorted. Thanks for all the advice in the thread!
Bit of a side note, I’d had my front pads and discs and rear pads replaced a couple of weeks ago. Also had unnecessary pre-sense activation where ABS kicked in briefly shortly after that. Wondered whether the restricted servo message was a result of those things, but not seen others in this thread refer to similar so concluded the timing was just coincidence.