Incorrect Service Charge for 2 years

I had an overdraft in 2015, which I paid off and subsequently cancelled. Since then I have been charged R4 each month for overdraft insurance, which I no longer even have. I have emailed customer care and a Joseph Fallie as well as the Prestige desk to no avail - they literally have ignored my many emails since 2016. I am currently at my wits end I have all my accounts with Standard Bank, have a perfect credit score and am loyal to the brand, and completely perplexed by their treatment of me. Perhaps another bank would prefer my business.