Hmm. I know there were other issues with this GP, but if the only issue was him insisting that you have a GP diabetic review at his surgery, then we are all in the same boat. All of us have to get a GP diabetic review, usually in addition to a hospital one. It's mandatory on the GP and they suffer penalties if you don't do it. So this is probably why he was using the strips prescription as a lever to try to force you to come in for the diabetic checkup. And he is probably relieved that you are off his books as you were refusing to do it.
As I've said elsewhere, even though it's a PITA and some time off work, I try to look on the positive side and think of it as some extra information (test results) and an extra chance of sporting problems early.
So you may get less traction with this part of your complaint to the PCT, as with the other parts of the complaint.