Unacceptable Practise

I took a personal loan with ABSA but due to COVID I was strained financially and couldn't pay back the loan. Eventually made a plan to get my finances in order. When I wanted to pay back the money I was told my debt had been sold to VERICREDIT and had to pay via them which I did and finished up my debt. Now that the account is paid up I can't get hold off the debt collector their numbers are not working to get my paid up letter. This is affecting me because I have to be in good standing to get a job and when my credit back round is checked the ABSA debt shows up and this is affecting my financial income. My issue is ABSA is selling our debt to none credible institutions and leaving us in disarray.