Frustrating Xtra offers experience.

I received an Xtra Offer email from Checkers. One of the specials was "Buy Any Pepsi Soft Drink Bottle 2L And Save R5" I went to Checkers Hyper at Brackenfell and the price was R13,99 per bottle. But when I got to the till, ONLY R4 per bottle deducted. (I took 6 bottles) I asked for a supervisor and along came Rhusay. I showed her the email, and she said that that specials is not valid at their Checkers???? I always receive email special notifications from Checkers that reads: NO COUPONS, CODES OR FUSS. SIMPLY SWIPE IN-STORE TO REDEEM! This special is Valid until 22/02. Rhusay also refused to correct the price and said she will only call Xtra savings first. I was VERY late picking my kid up from school due to this long process. I did go to the lady manager (didn't get her name) and she told her to correct the price. I am REALLY unsatisfied Checkers. I felt like a ******** and more I asked Rhusay to speed things up because I was really in a hurry, the slower things took. If this is what your promotion emails are like, I would rather not receive them. How many other people got caught out like this?