Shocking service

I have to say I am very disappointed with the service I received today at VW Barons Woodmead, I took my wife's car for a service and everything went well until I went to pick up the car, the service adviser(Le Ann) went through the amount that I had to pay and I told her my wife told me I don't have to pay anything for the service and she started to accuse me that when I brought the car she asked me and I said I will pay through a credit card and I DID NOT tell her that as I knew my wife had service plan and maintenance plan on the car, I hate the fact that she accused me of saying that I said I will pay and I did not, and after that she just started to be all unprofessional and red the she said she's just doing her job and she cannot help me, her manager had to convene and ask what the problem is and she explained to him and he managed to put in some few calls and sorted it out. After that she came and gave me the car keys and never gave me the receipt, I have never seen a person who can't handle pressure like her. If she had no **** that I said I will pay she would have solved this issue without my presence as I had to leave work and to go pick the car to be delayed by her,