Conns Did not auto draft my payments, made me 30 days late 2 times Beaumont, Texas

I gave Conns and auto draft form for my monthly payments. Conns argues that they never got it so the reported me 30 days late twice. I only found since I have credit monitoring and got the alert.  I immediatley paid them and was promised it would be taken care of. After may phone calls and emails Conns will not remove the black marks from my credit report even though they should have been billing my card on file.  They argue they don't even have the form. Great way to be treated by a company you have been doing business with for over 15 years. Looks like legal action may be my only option here.