incorrect billing, passing the buck to discovery

I have had unusual debits for my gym membership, discovery has told me that i should not be experiencing this and that my membership is still the same, last month i was not debited at all, this month, understandably, a double debit was taken, however there was a rather large debit taken as well, in total my debits were over R800. i am not sure why this has happened but i want it resolved immediately as I did not budget for these extra amounts. it is highly unfortunate that this has happened and i hope it can be resolved promptly.