HI Dave
Wish you luck trying to get any problems you have over to Motability in writing.
I’ve never had anything in writting personally written to me in the 13 years I’ve been with Motability other than contractual stuff that’s written by lawyers and on their terms or carefully worded stuff from their customer information pages.
I always use their contact us form that’s sort of email so recorded messaging system but they always reply by phone.
Ive never used the Live Chat system so not sure you can download a transcript of what’s been said like most companies do but yes, they don’t like putting anything in writing if they can help it and with Live Chat if like others I have used often have restrictions on time or how many words you can write.
Not sure how well letter post works with them but with stamps costing near on a Kings ransom these days its an expensive way to communicate, more so as your letter might get lost in the waste paper bin.