ABSA makes a mistake, I pay - still no response or refund

I have a payment pebble that I have been overcharged for, for months now. I have sent numerous emails (as well as the pricing one as per my contract) to absa merchants with no resolution. I have escalated the query twice and still no answer. I just get a 'it has been escalated and we are awaiting a decision' email every time. I am sure Zenith who is dealing with my query must be tired of me asking basically every day now, for my query to be resolved.