AMOUNT DEDUCTED MORE THAN AGREED UPON

I signed a contract with Virgin Active, Montana during July 2015 for R350 per month. I requested the sales person that I would like the debit order to start from 15 Sep 2015 as I will not be in the country for most of august 2015. On 1 August 2015 my bank account was debited for R350. on the 15th of Aug 2015 my bank account was again debited for R350. R700 was taken from my bank account by Virgin Active for the month of Aug 2015. I wrote to Virgin Active on 20 Aug 2015 informing them they cannot just deduct money as they wish. I signed for R350 per month to be deducted from 15 August 2015. I then requested Virgin Active to cancel my contract as I am very disappointed in hos this process was conducted and they just deduct money from MY bank account as they see fit. Every time they called me I requested them to put it in writing as I would like to forward the emails from 20 august 2015 between myself and Virgin Active to accounts department as they say I am in arrears with my account. They don't put it in writing, they continue calling me and today I received an sms from Virgin Active informing me that Ive been handed over to their attorneys. I need advise and help please!