Incorrect billing and terrible support from the Finance department

Incorrect billing for the 5th month in a row. Originally I was promised to be migrated from my 50mbps account to the new 250mbps account at the same price of R760p/m but I have been paying R799 since then. I have sent numerous emails and logged numerous tickets, I have originally received an email stating that they will fix the billing issue.

Last week I had to call support twice before they got someone from the accounting department to answer, while I was talking to them I asked if they reviewed my emails and they said yes and then I asked why they did not reply, I got no answer, I am also still waiting for a reply on the account issue also.