Over billed

I called Virgin Active call center December, ask the agent to freeze my account for January and February 2016, meaning January and February I will be paying R140 only. February my account was billed full amount, I called the call center again, explained that my account is supposed to be frozen and should only bill me R140, the agent responded that it has already been billed, they can't reverse it, but she will make sure that March they billed me R140 but my account will not be frozen since I'm going back to the gym, this month they billed me again my amount which was supposed to be 140 only, I'm really mad cause I can't keep on calling the call centre and when you give them a simple instructions, it is still not done correctly. Virgin active, I want my R140 reversed and I don't want to be told that they will do it next month. This is inappropriate.