Double payment and virgin active owes me money

I double paid Virgin Active. On the 2nd of August and then their system did not update as paid so I paid again on 5 August. Then on my bank statement it shows both payments actually went through and Virgin Active need to update their system and refund me the extra payment. I spoke to many people via email but no one even checks the bank statement or proof of payment I sent to correct this. No one is listening and its nightmare getting my money back.