bad service/attitude

I was in the Lenasia store(Trade Route Mall) yesterday and was excited of the new cricket card campaign that is running currently. To my surprise when I was making purchases, teller advised me that there is some items that don't qualify for this reward. There was banners in the store advising, "Any item purchased to the value of R150 you would be rewarded with the card". I purchased a google card for games to the value of R150 and was advised that this doesn't qualify. I requested to speak to the manager and was also advised the same. Manager(Customer service manager-Maria) refused to give her surname as her name tag doesn't have that information either. WHY DOES A BIG STORE LIKE THIS HAVE FALSE ADVERTISING. THEY SHOULD STATE THEIR TERMS AND CONDITIONS ACCORDINGLY AND CLEARLY TO CUSTOMERS. Generally the store managers have a bad attitude as well. They like to argue before finding a resolution.