Ring Mota, they should allow a change as it’s due to a change in medical needs, I have had to do this twice (both times I was unhappy to let current car go as I liked them so much and wasn’t able to replace with same car in different spec), they did mention the £250 fee but waived it both times even after offering initially to reduce it to £50 when it came to the time they just said it had been reduced to zero.
Don’t struggle along with it as I did for a year as all that did was make my conditions worse.