*****ulent transaction

I wanted to buy a virtual office space on regus.com, the system calculated a prorate for the current month of April, the amount was 572, it took to me the payment page with 572 displayed as the amount I am paying but once I put in the otp and submit, I was charged over 2300, I can get hold of anyone at the company, calls just goes to voice mail. This company is a *****ulent one, they used one otp to authorize multiple transactions without my consent.