ANNOYED!!!!

I have my car insurance with first for woman and we have been having long discussions about the policy and how they have worked the policy out, etc. We then eventually came to an agreement and an amount and from when they will charge me that amount. This morning I get up and see that they have taken my policy off, but it is the incorrect amount, as it is only supposed to be going up as from the end of April and the amount they have charged is TOTALLY TOTALLY incorrect. They have also taken the policy off late. I don't understand that after how many discussions we have and everything else that they can still get my policy incorrect.

unfortunately I have to have insurance on my car, if I didn't I would immediately cancel with first for woman and go to a more reliable insurer, if there is one