Bad service from Woolworths head office

I missed a payment in July then on the 23rd of August I paid my acc using internet banking. For some reason the payment did not reflect on their side and i only have to find that out the following Friday when I viewed my balance at the store. Went to finance department and they requested proof of payment so they can update on the system. Saturday I went back with the proof and it was said they will update within 3 working day that was the 30th of August 2019. Following week went to the store to buy only to find out nothing has changed they didn't update anything. Again I inquired this time they told me someone made a mistake and logged R20 000 instead of 2000. So they need to verify how much i paid. With that sorted still the problem is not sorted. When I phoned again The guy I spoke to told they dont even have an update on my case. Friday I went to the shop and this almost a month , the finance desk phoned the head office and they said I never sent any documents. Now i receive a call from debt collectors for the account I paid,