firstsource financial solutions llc firstsource financial advantage llc Offered me a lower amount for early payoff and reported me to credit bureau for paying less than amount due LaPorte, Indiana

My city was hit by a tornado causing the roads and electricity to be out for over a week.  My payment was due with Cullman Regional Medical Center on May 1, the tornado hit April 27.  Since my payment was late Crmc sent my account to Firstsource Financial Solutions LLC. I spoke with an agent several times and asked if this would go on my credit, she said as long as I paid it within 90 days it wouldn't but if I paid it off in 30 days they would give me a 20% discount. 

I did everyting I could to pay it off, I sold my car the only thing I owned to not have my credit affected.  Then I had a company tell me I was a medium credit risk.  So being as to how I have outstanding credit and have never NEVER had  a late payment I ran my own credit.  Firstsource Financial Solutions  reported me for paying less than the amount due.... I NEVER asked to pay less,  their representative offered it as an incentive, and the reason it even was a topic is because I didn't want my credit affected. Please help me.  I am self employed and can't prove income so good  credit is all I have. Thank You