Bad service

I took out a car warranty with FNB last year November, i specified that I would like my debit date to be on the 25th. They assured me that the first premium will go off on the 1st and there after premiums will go of on the 25th as per my request. I called yesterday to enquire with them as I wanted to take my car for service and that's when they informed me that the warranty was cancelled as they did not get the premium. I was not notified of this and also they did not stick to the debit date as per my request. I have called several times but I'm not getting any joy