RCS Deb collectors.

I'm having the worst experience i can think off. I received a account in 2020. I paid the account in October 2020 for the last time. The outstanding amount was R234.00 and i paid R240. To this day i am being harassed every month by a different attorney company for this payment. I keep sending proof of payments and emails. But still today again it is another company. This is now 2021 November. Is it just me or is there more people? Do people just keep paying? when does it stop? I can't handle it anymore. My co-worker said she has the same problem. Every Company has a different ref no:

What must i do?