I have been fighting the DWP since March 2021 to try and get PIP.
After the MR they still had awarded me only
2 points, so MacMillan's suggested I try to get a Doctor's letter ready to go to appeal.
Got the letter sent off, free of charge btw, on Thursday got a call out of the blue from the DWP saying I had been awarded the enhanced rate, 12points!
So I would say, even if you have to pay for it, it's worth getting a Doctor's letter