The issue is not whether the property charges a "hooker tax" but whether the wife was properly registered. If so, she should simply have produced her room card (key) and be done with it.

Under the circumstances, this should be dealt with on property. 99% of issues are best dealt with in person.

Chances are that unless OP and his wife are the only couple staying at the property, this issue has arisen before and the more it is brought to management's attention, the more management is likely to fix it.