Calling for accounts already paid

Intercare Glenfair sent me an invoice for a doctor's visit on 7-12-2017 - which was paid on 8-12-2017 at their offices. That same day I get a phone call that I owe them money.

On 8-12-2017 I had a follow-up appointment, which was paid via EFT & POP sent that same day. The outstanding amount was not sent through only via SMS.

Now I get a phone call that I owe R147 - which was already paid - the person calling me refused to believe that I paid, and I sent through the POP again, just to receive the statement of the money 'outstanding' which I already paid! This is so annoying, as someone who settles accounts immediately, to be treated this way.

Perhaps Intercare Glenfair needs to get more organised in their Billing department.

I don't want to be contacted by the institution. I just want people to be aware that this happens, whether you pay or not.