Billing error not being addressed

I cant wait to terminate my contract. Your mysterious "back office" is non-existent. I logged a dispute on my billing on the 9th of December 2020. To date no feedback or reversal has been effected. Your call centre agents keep sending me from one department to another. All they tell me is that the matter has been escalated to the finance department. Surely it doesn't take 11 days to resolve a billing error? Do you even have a finance department? You do not care about your customers. If this is not addressed by tomorrow, you might not get anything from me this month - you are taking me for a ride.