poor customer service

My account was handed over in 2022 without my concern, no one callled about the overdue amounts

I paid the account via debit order for about 6 months, about a month ago I received a call gain from the people the handed me over to for an outstanding balance they could not debit because it was less than the amount of the debit order arranged

I am still receiving threatening SMS's and calls of an outstanding balance off which it keeps on increasing everyday

Can someone please assist this is disturbing me mentally I don't know for how long should I be paying Isabella Garcia

I have bought so much airtime trying to call back the people that call me but no answer