GWM car service / service plan authorization

Being a client of GWM for over 10years and serviced my cars with them all these years. Never had any problems with services and them getting authorization from my service plan until yesterday. Apparently it was wrong of me to think they know I have always had a service plan like the last 10 years. Now Liquid Capital is querying why they serviced without authorization, and GWM is refusing to give my car back without payment. Please be careful of signing any paperwork with GWM when it goes in for a service. I will never again in my life let GWM service my car as they try to fool you for every cent you have.