I can only give my own personal opinion but I have always found the Motability customer service operators unfailingly helpful. I make a point of being pleasant and to the point, and I have never failed to get a satisfactory outcome (I’ve been on the scheme for almost thirty years). In this case I would clearly report the problem to an operator …. point out how essential RAC back up is to a disabled person …. insist on a call back when the RAC registration has been successfully sorted. Job done, and all in a very polite and friendly manner.
Agree, obviously phoning does often involve being on hold for a while, but once speaking to them I have found things get sorted. I found the process of registering my vehicle on the RAC app very straightforward. Of course I need to say that phoning is not possible or easy for some, but if that’s not the case I would phone every time