Biltmore Hotel Miami review: Double fees

I stayed in this hotel from August 10 through August 14. I made the reservation directly with the hotel. When I departed I noticed that I had been charged a daily fee that was already charged in the original invoice. The employee at the reception told me that my reservation was made through Expedia and that Expedia should be responsible for returning to me the extra charges. However, later I learned that the reservation had been made directly to the hotel. When I complained to the hotel they asked me to give them the invoices. Don't they have copies of the two invoices? I think this is a normal practice at this hotel where they charge people initially and then charge them again on departure. I would like this case to be investigated because there might be more victims of this fraud.