Virgin Active has been somewhat dissapointing

I have asked Virgin Active to supply me with any evidence showing that I agreed to a monthly premium of R1460. In fact my premium should have been around R800 for the past 4 years at least. I have found out that this premium actually belongs to another member and to top it all my premium was being taken off a third party's bank account. (hope the explaination makes sense). All i am asking vzirgin to do, is to show me where I signed for this larger amount and I will accept it. After numerous calls and emails I have made absolutely no progress. this month they got even more clever by taking BOTH premiums from my account. Go figure? The communication is shocking and the admin is a close second