MightyDuck,
Don't be discouraged. Looking from the inside, you really cannot judge how much progress you are making. Myself a slow learner, I spent several times an hour or more running touch & go's, and drove home with the feeling the last circuit was no different from the first. Yet one day I was suddenly sent up solo - and managed quite well, to my lasting delight and surprise. Certainly every student will pick up some points easier than some others - sideslipping came naturally to me, and I still enjoy it a good deal; whereas some fellow students told me they remain uneasy about it.
BTW myself had two instructors and that was a nice formula for me - they each had their style and their habits, and I knew what to expect from each. I could not have managed more, I think.
OTOH, you are passing a good deal of money and you should have some say in the way it is spent. If you request to have one single instructor your flight school should be able AND willing to arrange this - otherwise you had indeed better find someone else on whom to bestow your hard-earned pecuniaries.