Unless you have willingly agreed to the changes, 3 different instructors in your first 8 lessons is not good enough.
One radio call in 8 lessons sounds odd, but maybe that is part of the school's method - I don't know.
Saying you don't blame the school in any way is little naive. Maybe, as hinted, you are not reviewing your flights sufficiently or carrying out the necessary ground prep and study. Maybe you are not cut out for flying (it's not for everybody). Or maybe the instruction is not all it could be. If you really want it (and if you are not committed walk away now) start off by putting more effort into your ground study, whilst telling the flight school you only want to fly with the same instructor for the next 10 or so flights.
Tip, find out which of the three instructors are unrestricted and stick with them. They are likely to be the most experienced and they will be able to solo you without having to hand you on to somebody else at a crucial stage.
If the flight school don't respect your input, find another school.