Murphy USA

I used my Walmart Master Card to purchase fuel. After we left the pumps my wife looked at the receipt and noticed that we did not receive the 5 cent per gallon discount as we should have. This location was at WalMart, 7855-A Moffett, Mobile Alabama. Site 6987. Price charged was same as posted with no discount $1.899. I purchased 16.4 gallons so I paid 82 cents more than I should. This was on 9-17-15. My wife also looked at a gas purchase in Magee, Mississippi Walmart that also did not include the 5 cent discount. When we arrived home today, I stopped at the local Bossier City, LA Walmart and filled up with gasoline and received the 5 cent discount as normal. Why did I not receive the discount as avertised on the pumps at these locations and what are you going to do about it? Thank you Larry Johnson larry3johnson@aol.com