Bad service

I have paid my account in full with Finchoice in August 2019 and till to date I am struggling to get a paid up letter with the correct reference number for that account . Hence now I cannot clear my name and move on with my life. I have tried to calling their legal department but no one is answering the phone. Their call center can't help either. I have spent a lot of money on airtime trying to get through. I have sent emails but still the matter is unresolved. Please assist