Product: Credit reporting or other personal consumer reports

I was talked into taking our a line of credit at XXXX XXXX through XXXX XXXX. Originally offered a XXXX line of credit. The idea was to earn a value towards my next camping world need. I used around XXXX dollars to pick up a washer and dryer. This was in the summer of XXXX. I made XXXX payments right away combining to around XXXX and was left with a XXXX balance. The we planed a trip to Alaska to move out of our house and fill a tailer XXXX XXXX it back down. This process took a solid XXXX months but the first and third month might as well be included as a preparation and recovery. For XXXX months I was on XXXX XXXX and busy moving and cleaning basically and during that time XXXX Bank went through a upgrade on their online banking software. Since I was on the road and not in our new home I did not think to have the first bill with me as that is the only document with the account number. However, I was unable to login without the account number and XXXX XXXX  would not share the account number over the phone. Every time I called in my balance was XXXX because I had basically made XXXX worth of payments towards the balance. I was never contacted by XXXX XXXX  in regards to a missed payment and thought I was good with them for a few months since I had made such a large payment. XX/XX/XXXX I get a notification from XXXX XXXX that I had serious late payment delinquency on my report and my FICA score bottomed out close to XXXX points from XXXX to XXXX. I immediately called XXXX XXXX  and challenged the reporting and pleaded with them to remove the negative reporting. I also paid the balance off and canceled the card. So not only did I feel like this was a misunderstanding but also they got paid back very fast. Since then I am unable to use credit for anything. I can not refinance my vehicles or trade them in for better options. I am afraid to even try buying another house. I make really good money now and need to lower some payments to improve my budget for living the paying off more debt. I think its possible they won't fix it because I canceled the account also which would be retaliation. I spent months calling them and working on getting to the right department to analyzed this and correct it out of courtesy or compassion as literally destroying my financial life over a few months with they were changing over the own software and telling me on the phone I had a XXXX balance was on them also. I paid them way more then necessary and still I am unable to swing a loan because of reported late payments on my report. I wrote them a letter and mailed it which is the only way they will answer a dispute like this and finally they responded XXXX months later with formal letter explaining that they are right and won't fix it. No details as to why they were right, or documentation of attempted phone calls or emails. Nothing! I feel like because they were changing software and making it very hard to login and see balances and make payments they should remove those negative reports. To this day XXXX years later I still do not qualify for loans based off this. I do not see why a misunderstanding inquiring such a small amount of money and directly affect major life changes.