Canno get anyone at Europcar to take my call

I have been trying to get hold of someone to assist me with an amount charged for the hiring of a car. I have been shuted from one person to another and then get cut off. I call back and after the person answers I am put on hold and music playing and still not able to get hold of anyone to assist with the incorrect Invoice charges. Can someone please assist as I cannot understand how they were voted best car rental when I cannot get anyone to answer my questions?