Are they actually qualified teachers? I have pulled DD1 from hers as despite the teacher assuring me she taught at different levels, taught them all from the most basic level. DD1's French is pretty good and there were others in the group who also had a reasonable grasp of the language. I did raise it with the teacher and she said rather snottily that revision was always helpful.
I also thought her French was rather crap - spelling mistakes in things she had written - not the printed sheets.