Simple. Call your CC company and dispute the charge. The real estate company has to show you agreed to pay whatever it is you think you don't owe, or the CC company simply reverses the charge and you don't pay.
One BIG reason for using a credit card over a debit card or a check.
I got double billed for a set of cabinets once from Lowes, and would not pay it.
Told them "show me two different invoices where I SIGNED for them, or fix you billing procedures"......end of bill.