Hi-fi Corp give me my settlement letter

I am so ****ed off by Hi-fi Corp right now they rob people of their hard earned cash. I took credit with them(the worst decision i have ever made). I paid off all the money that i owed them and asked for a settlement letter, i was told it would take 3 days for them to email it to me, after 3 days they suddenly said i can't get a settlement letter there's money that i owe (monthly service fee)... I told them they already charged for service fee for the month, they are turning a blind eye on what i tell them. The agent told me last week friday on the 3rd of july 2020 that he has escalated the matter to accounts department but the accounts department is not responding. I have to waste my airtime almost everyday, waiting for the next available agent, it hurts me that they don't take me serious as their customer all i want is a settlement letter. I know for sure that they have lost me as their customer and i will make sure that i spread the word to people i know. I will not be treated like this, i work very hard for my money, they must reverse the money that they have added and give me the letter.