Unwanted debit orders

Good Morning FNB. I am your client for years now and i pains me that i forcefully have to part ways with you like this. I had a contract with a certain car insurance company which i went on to cancel a 2 months ago but everytime i deposit money into my account they deduct their "Monthly premium" and i can't even reverse or dispute. I went to one of your branches and i still couldn't be assisted. I think the next option i have is to switch banks because i can't be bul**** of my money while im your client.