Virgin Active ZERO customer service!

The most shocking experience I have ever had in my life! Their debt collection agency has been harassing me for the past 6 months with ongoing calls and messages at unreasonable times of the day and night demanding payment of an outstanding amount of R 460 which I paid 6 months ago. Virgin Active has confirmed my account is paid-up however they continue to allow their debt collection agency to consistently phone me rudely demanding this money. I have wasted an extensive amount of time going into the Virgin Active Wembley Sqaure branch, speaking with the manager, making countless telephone calls, sending emails and SMS proof of payments with no resolution. Virgin Active is telling me it's not their problem as they hand their book over to the debt collectors. The fact that I queried ever owing Virgin Active the outstanding amount I eventually ended up paying is another matter completely as despite me asking numerous times for them to send me proof I owed the money I never got sent anything. So, I eventually just went ahead and paid the R 460 to get the debt collectors off my back to no avail as despite this they still keep bugging me 6 months later. I am desperate as I can't even block the debt collectors as they keep using different numbers.