Overcharged Payments with Currency Exchange

I have been overcharged by Airbnb over and over again. I have just booked accommodations in Italy and was quoted the price in USD. However, I was charged in YTL despite not having any bank account connected to Turkey in my Airbnb account. Airbnb converts the amount to a foreign currency and takes a hefty commission actually without doing anything. Now I will also be charged by Amex for a foreign currency conversion. It is daylight robbery actually. Despite me taking precautions to prevent it, this has happened again and again. There is also no way of contacting Airbnb – no customer service whatsoever.