Threats for their own error

This is not funny anymore. When I took the policy I advised that my debit date tobe on the last day of the month and now I have been receiving smses that confirm you will be going into my account 3 days before my required date and for April you went in on the 24th which is 6 days before the debit date and then you sent me an email saying you would charge me an additional 60. I called and asked about that on the 26th and was told it has been updated. Today I receive a threatening sms that I missed payment and you will cancel my policy. But whose problem is it that you went early into my account. I called again and wan on the phone for 20 mins with Sylvester Ramalepe who was no assistance at all as he confirmed that I changed the date and I never did that. Can someone sort out this mess urgently as its not my fault.