Horrible Nimble Group

Horrible agents phone calls. No resolutions. I even went as far as to write to Mr Rowan Gordon out of desperation. No reply as yet. Dear Mr Gordon, My apology to contact you via your private FB platform, but I am desperate and resolution not possible with the continuous telephone calls I am getting from the Nimble Group. When I ask to speak to a manager the phone is put down in my ear, hence me following this route. I had a Finchoice account which I settled in full, with the discounted settlement amount given to me by the agent. The amount that remained after the discount was awarded was never "written off", this the agents are phoning me daily at work claiming I still owe this amount, where in actual fact the account should have been closed already. The second challenge being I will not receive a paid in full letter for this account. The agents are rude, one telling me I must not be cheeky with her, I am explaining myself daily and nothing is being resolved. The whatsapp group is not operational, I am not being answered, I have send emails, no one responds, I have tried phoning - that is close to impossible to speak to anyone. i am also receiving sms's with-"Immediate Payment due" I owe nothing on this account, at the back end someone did not action their part. My ***. If you can please assist me I will be grateful, I cannot continue with this on a daily basis and I would like to resolve as this can give me problems in terms of future credit applications.