Overcharge on Monthly Fees

I am a long standing client with Nedbank, with a Credit Card for over 10 years now. I recently noticed that they overcharged me on my monthly fees for June. I called through on Monday, 15 July 2019, and enquired about it and was told that it was Mays' fees that was also deducted in June. I checked my May statement and saw that I was indeed charged in May for May, so they incorrectly charged me in June. The call centre agent was not clued up with the correct information and could not assist and she referred my query to the Credit Card Specialist. I am still waiting for the call back from the Specialist to resolve this issue. This is really bad service and empty promises from Nedbank especially since I am a longtime customer. They don't even deserve the 1 star rating given.