Billing account and bad attitute

On the 30th September 2017- I went to the Festival Mall Donna-Claire to exchange a denim dress for a smaller size. Firstly the staff in the story very unfriendly, there was only 1 friendly staff member is that store- she can teach the rest of the staff that. Eventually when I was assisted the lady was very unfriendly and ***********, I came to exchange the dress for a smaller size, I didn’t look at the receipt when I left the store as I was already annoyed. I got my statement and was shocked to see my balance has increased so much. Only to find out the lady charged me twice for the same dress, how irresponsible is that now, it makes you wonder how many customers was charged for things they never took from the store. I unfortunately cannot go back to the store just to be annoyed by *********** staff and would appreciate if the reversal on my account can be done A.S.A.P and would also like a letter of apology from the Festival Mall branch as this is highly unacceptable.