Product: Credit reporting, credit repair services, or other personal consumer reports

The purpose of this letter is to explain the details about my accidental oversight on a utility bill payment that is now negatively affecting my credit history due to having been sick with XXXX. 
I have owned the property on XXXX XXXX XXXX XXXX XXXXXXXX, AZ XXXX for over three years now. In XX/XX/2020, I decided that it was time to move from this area to raise my son in a better environment. In XX/XX/2020 I started coming down with symptoms consistent with XXXX. On XX/XX/XXXX I took a XXXX  test at XXXX XXXX XXXX XXXX. My results came in on XX/XX/XXXX as being Positive for XXXX. I had previous arrangements to meet with someone to sign a lease agreement. With the proper precautions we met and executed the lease agreement on XX/XX/2020. 
Soon after having an executed lease agreement I called all the utility service companies ( including XXXX ) and cancelled the services because the tenants would be soliciting services under their name. I paid what I thought was all pending balances for the services up to the current date. My symptoms due to XXXX worsened by the day. I became bed ridden and not able to tend to anything besides my immediate physical needs. My head felt disconnected from my body and body hurt so much! I lay in bed for a over week, but I did pull through. 
Once I started feeling able, I got back to working on my plans to purchase a home in another area. When speaking to my loan officer, I was made aware that my credit score had dramatically been affected by a late payment to XXXX that had now been sent to collections. This was a big shock for me because I had no idea that I had any balance pending with them and believed I had completely paid the account in full. Had I missed a payment and not been sick with XXXX I believe I would have kept up with getting my mail from the tenants and noticed a past due bill and paid it right away. XXXX had severely inhibited my ability to think clearly and my ability to complete everyday tasks. It would have never made it to collections had I not gotten XXXX. 
I called XXXX and paid the outstanding bill, but the account continued to reflect in collections. I called the collections number and with my broken XXXX asked to speak to a XXXX  speaking person but the person that answered said that I didnt need to speak to anyone in XXXX. As best as I could, I explained to him what happened and told him that I had proof of having been very XXXX  and of the house being rented and that I had no idea there was a pending balance. 
I paid the balance and even paid to have this resolved by a credit repair company and after two rounds we still have not been able to get this removed. Before getting XXXX I was qualified for a Conventional loan. This was the only payment that I missed while sick with XXXX and it reduced my credit score by about 120 points!! I went from qualifying for a Conventional loan with a good interest rate, to not being able to qualify for a loan at all, not even an FHA loan. I work hard, I take my credit very serious and always pay all my bills on time. I purchased this current home with a Conventional loan because of my good credit and work history. But now because of an honest oversight while sick with XXXX, my scores have plummeted. I plead that you help me in removing this collection mark from my credit history so my credit score can be restored. This is affecting my ability to better my future and that of my young boy. Thank you in advance for taking the time to help me with this. 

Best regards,