Thrifty Rent A Car review: Billing issue

I recently rented a vehicle from Thrifty at Tampa Florida Airport after returning the vehicle about a half hour later i received a bill on my phone for $497.78 which I found odd because I paid for my rental prior to picking it up so Im reading further and I see this insane charge for $400.00 for outside washing... I have never heard of such a ridiculous charge before and I refuse to pay that. I started reading reviews about thrifty car rental and couldnt believe how many complaints there were for added charges about this company, they have no live customer service to even talk to about removing this crazy charge from my bill, I will be contacting everyone and everyone possible about this scam