Dufry Duty Free Shop Puerto Vallarta, Mexico Got Scammed Puerto Vallarta, Other

My husband and I were returning to Canada after spending 2 weeks in Puerto Vallarta, Mexico. While waiting for our plane we stopped in at the Dufry Duty Free Shopt and I asked about the price of a purse. The sales lady told me it was 50% off. I asked her what the price was with the 50% off and she took a hand held calculator and entered some numbers and showed me the number on the calculator and said it was 92.00 US. I left eh shop without purchasing it and my husband and I went for dinner. After we ate I decided to go back and get the purse and the same thing happened. I didn't ask how much the purse was this time but the sales lady told me the exact same thing, said it was 50% off, she took her calculator, did the conversion and showed me the exact same amount of the purse as before, and said 92.00 US. I said I would take it. She started using a cash register and told me to come with her and she took me to another cash register saying the other one wasn't working, she tried to enter the sale again and again she asked me to come with her to another cash register and as we were walking to the 3rd cash registered she stoped and talked to a co-worker in Spanish. This took a awhile and I was now in a rush as they announced the boarding for my flight. I signed the sales receipt as I put it on my American Express Card. When I got my credit card statement I was charged $938.00 US, close to $1,000.00 Canadian. I immediately contacted Dufry and for the next 2 weeks I sent them emails almost every day. Finally on March 6 they agreed to refund my money and told me to send the purse back to them and once they had it they would refund my money. On March 17 I checked the status of my parcel and it said it had arrived but was waiting at the post office for confirmation of address. For the next 3 weeks I emailed Dufry over and over again and they said that they knew te parcel was there and they had to do some paper work which would be completed that day and they should have the parcel by the end of the week. It has now been 3 months, and after many emails, someone returnd the parcel back to Canada, it was sent back to Mexico and finally on April 30 the status of the parcel was "item delivered successfully"  Now they are telling me that they are closed on April 30 so they don't know where the parcel was delivered or to who.  Today, June 9th I am still unsure where the parcel is, I am out the money and they also have the purse. I contacted American Express and they sent Dufry a letter and their response was that I signed the sales slip so they will not refund my money.  I will never again buy anything at Dufry never mind in Mexico again. We never buy from the sellers as it is, thought a duty free shop was pretty safe, but were we wrong!!