MAPCO review: Coke discount and bad customer service

My husband and I go into mapco all the time to get their big drinks for.89 and.99 cents. Noone ever asks us for a mapco card or if we have one. The sign says plain as day.89 any drink. We go to pay after we get our drinks and the womsn who works the deli rang it up at 3.87. I said "maam the sign says.89 cents any size drink" "she said" "only if you have a mapco card". I said... Well can I get a mapco card so I can get my discount? She said "no you may not get a mapco card we ate not giving them. Out today" she was sooooo rude. I asked her well since I cant get my card can we get the drinks at the.89 cent price since everytime we come in nobody has told us this? She refused! We told her to keep it we are taking our buisness somewhere else. Very poor customer service