I HAVE BEEN CHARGE THE DOUBLE THAT IT SAID ON THE APP

Hello, i have just puchased the app for the first time, and i purchased the whole year with “80% off“ that it said. I’m from Mexico and o had to pay “399.00 pesos“ and I got charged “728.00 pesos“, which is almost the double that I was supposed to pay, PLEASE SUPPORT ME WITH GIVING THAT EXTRA MONEY BACK, because I bought it with the special offer, if it hadn’t been there, and if I had known that you price was the one I got charged, O would have acquired it in the first place. Thank you