Cancellation of the increase

When I join Old mutual, I made it clear that I want my premium to be stable, not to increase every year and they told me that I should write letter and I did write that letter.<br> <br> This year I received an e-mail informing that my premium will increase from R150.00 to R159.00, then I phoned them again to not increase it and they told me that I should write an e-mail, of which I did. And they promised not to increase it, later on I got an sms informing that my premium has increased to R159.00, I then phoned them again and they told me that it is automated sms, I should not worry about. <br> <br> So now they deducted R159.00 instead of R150.00 from my account. I want to know why and want them to fix it because it seems like they do not communicate properly on their side <br> <br>