Double charged

I made a reservation on the 31st of January. Payment was done via their website. On the early hours of the 4th of February another payment was deducted. When I make a statement it says one payment hasn't been processed the second one has been successfully charged. I tried making contact with them and they promised it would be sorted out within 7 days. I need to use the money for my mom's medical use as she's not well. Why does it take this long to get ones money back yet with them you can never make a booking without paying them