Product: Debt collection

I am being sued by Mountain Land Collections , LLC. 
The attorney for the plaintiff is XXXX XXXX XXXX XXXX XXXX XXXX XXXX XXXX XXXX XXXX XXXX XXXX XXXX. Telephone number : XXXX, email : XXXX This is for a medical bill for my son, XXXX XXXX, date of service XX/XX/XXXX. My son was seen in a XXXXXXXX XXXX XXXX XXXX XXXXXXXX XXXX XXXX XXXX, XXXX XXXX XXXX XXXX XXXX  XXXX, XXXX, XXXX for a XXXX XXXX XXXX XXXX The plaintiff is stating that I did not pay the outstanding balance owed to XXXX XXXX XXXX XXXX, with a balance of {$290.00}. I never received a bill for services from XXXX XXXX XXXX XXXX. I called them after receiving court documents on XX/XX/XXXX. They stated that they sent me a bill on XX/XX/XXXX showing the balanced owed after my insurance made a payment of {$1100.00}. However, I never received the bill stating I owed money for the services. They said they sent me a 2nd notification for the balance owed on XX/XX/XXXX, I also never received that bill. They never attempted to contact me again my mail or by phone. They then sent the debt to Mountain Land Collections , LLC on XX/XX/XXXX. Mountain Land Collections states they also sent me a bill on XX/XX/XXXX. I never received that mailed bill. They said they did not attempt to contact me again by mail or by phone. They stated they did not have a phone number on file for me. However, they did know where I worked and confirmed the correct mailing address. I have had my cell phone for 15 years and 5 months. I have worked for the same company for 14 years and they never attempted to contact me there either. I know it sounds absurd but I have no recollection of receiving any mailed statement, bill, collection notice, or request for payment. My phone number was easily accessible, it wouldn't be hard to search for it, had they tried. They also did not send any further request for payment by mail. There is no way to prove that I received any mail from XXXX XXXX XXXX XXXX or Mountain Land Collections, LLC. On XX/XX/XXXX I was served court documents at my home, I called immediately to resolve the debt but they are stating I have to pay interest, attorney fees, and court costs. I will pay my debt of the {$290.00}, but I don't feel I am responsible for the other fees as I did not know I had the debt. I'm sure people claim ignorance frequently but I truly did not know there was a debt outstanding. To show my good faith, I have researched my history for paying towards this medical incident. After my insurance paid XXXX XXXX {$1100.00}, I paid the outstanding balance of {$280.00}, I also paid the XXXX balance after insurance of {$2.00}, as well as all of the follow up visits with the XXXX XXXX XXXX  for the amount of {$58.00}. 
It makes no sense that I would pay all of the other debts but not the one in question. I didn't pay it because I did not know it existed. I want to pay the debt owed of {$290.00} but they will not work with me and claim I have to pay the full amount of {$870.00} which includes interest {$100.00}, Court costs {$130.00}, and attorney 's fees {$350.00}. I would like to resolve this without going to court and would promptly like to pay the debt owed of {$290.00} and close the account.