Avis over charged me and refuses to correct it!

Very disappointed with Avis. They over charged me for a booking. I sent them numerous emails asking them to rectify or explain to me why the charge was so high. The last guy that attended me decided he's just going to ignore my emails. What makes this worse is the this is a matter from last year December and still it hasn't been sorted.

The only reason they get one star in the rating is because i can't review without clicking on the rating. Otherwise Avis doesn't deserve a star at the moment.