Is there anything can be done, preposterous egag sales tax?

I don't think you "get it." If I walk into a local store and they try and overcharge on sales tax, that is ILLEGAL

Oh I "get it." You asked if there's anything that be done, and I answered. Sure there is. Either report them to the appropriate authorities; don't use their service; use their service and pay 40% 'sales tax' and accept it; or complain about it on a car forum. The choice is yours.