2014- I owed Cox Communication $X which was not communicated to me as I had moved out of the apartment, and there might have been only mail communication as no email was sent me.

2016- Debt Collection agency reports $X on SSN. I called Cox Communication and paid the debt directly to them. Debt Collection on my account is cleared.

2019- Debt Collection agency again report $X (exactly same amount that I had paid) on my SSN.

I called the Cox Communication they have no amount pending against my name. Called Debt Collection Agency, they gave me two options
1. Dispute debt and wait till the reported delinquency clears out.
2. Pay the amount get rid of it quickly.

I wanted to apply for mortgage loan and due to reported debt on my SSN my credit score has been impacted badly.

Would like to seek the legal advice on what should I do to clear out the reported debt on my SSN asap and reprimand debt collection agency.