If this is a credit card you can dispute the charges - ie no fees to be paid , interest or impact to your credit rating or limit.
Call then Send an email/fax to the credit card company and tell them to investigate the error as this is between the merchant and the bank.
Until resolved this amount should be put aside. Have done before with Visa, Amex etc and also usually ensures the merchants reply to be very quick but does take 2-3 weeks