Several comments about 'stubborn teachers'.
Please remember that pressuring teachers to inflate your predicted grades is actually very silly. Just think of the misery of A level Results Day when a student who applied well beyond their ability has just seen all their dreams come crashing down because they convinced that teacher they were 'good enough' for an A or whatever. They weren't and the teacher knew they weren't. And if they'd listened to that teacher they'd now be happily going to Uni instead of crying their eyes out and scrabbling about in Clearing.
Getting Offers way above your real ability because a teacher has over-predicted is pointless. 'I've got an Offer from Durham' might sound terrific, but that isn't a PLACE at Durham. You then have to GET those grades to get in. And reaching exam season, and knowing there is probably now no chance of you doing that well, but you are holding two ludicrously high offers is probably a guarantee for the most stressful summer possible.
Accept your predictions. Use them as motivation to do better, but don't ask teachers to inflate them. It isn't worth the pain.