Account Paid in full and still handed over after!!

I took my mother to Intercare Woodhill 2014, we paid the copayment upon leaving, +/-6 months later we were contacted by a lawyer to say the account was handed over, we had no communication that there was an out standing amount, I went into the office & they said that due to a postal strike, no accounts were sent out & no email was sent as there was none given on her account, even though my email address was given as a reference. I paid the outstanding amount & it was deemed as settled, the lawyer continued to harass me +/-6 months were I constantly sent the proof of payment but the matter was only dropped in 2015. I took her for the procedure on 13/05/2015, again the copayment was paid, however the full account was not sent through to the medical aid, only the medical tariff & they then give you the outstanding account, I asked them to put through the full amount, so that whatever is not covered could be claimed from a gap cover. This was never done, after numerous visits and fights I eventually paid the outstanding amount of R874, I have now again been handed over as they claim there still money outstanding, my statement show a R0 balance???!!! Most unprofessional service!!!!!!