Service manager says doing favour when I have warranty

Joch the service manager had no way how to speak to a customer there no such thing as his doing us favour that's what he tells me cause I told him off he treattened me he will make sure he drops my warranty cause I told him there's no such thing as favour when I paid my money,his saying his the manganer n ford will listen to him ,as a manager he has no customer service my van was there for 3 days just to do brakes then to hear that I mustn't complain cause his doing me a favour