I had a few problems with my first instructor as I was one of those "you don't know what you don't know" students. However, the crap hit the fan just before my PPL test when it was discovered a few significant training factors had been overlooked. Anyway, I put it to the owner of the company and the CFI that I refused to train with that person again and changed to a much better instructor. Then for my IFR I flew with the CFI and we both knew where we stood, re. my ability to perform and who was paying the bills!!
Don't for one minute think that just because you are under someone else's command you are worthless. YOU are paying their wages, and never doubt the power of letting them know that either in the cockpit or on the ground in front of senior staff!