Trying BS to get more money

My insurance rented me a car through Avis. I drove it for a month and had unlimited kilos. Gave the car back, clean and the guy inspected it. All was fine. Couple days later got my deposit back. The a ***ard called me. He told me I was suppose to take the car for a service on 15k km. I told him that that was not stated anywhere in the docs given to me. He told me he'd call me back. The ***ard never did. The 8 Dec I get a sms telling me I owe over 6K. I know I should pay some tolls, but i didnt spend 6K on toll gates. So I called your call centre and I spoke to a girl and she said they will look into it, and it is not a problem. I told her its a massive problem. She said accounts will call me back. Now I just got another SMS. ***. Are you all ***ards. Cant pic up a phone? Tell me *** is going on. I will pay for the tolls and not a sent more. BTW no one told me the car must go for a service and even Kia state on the website Minor service every 10K km bigger every 20K and major every 40K. So why tf must I do it on 15K and if no one told me that how must I smell ur service history on your cars. If you give me access to your systems, a login and a small salary, then I will track this. Maybe then I can try and ***** someone else out of money too