Vishal Mega Mart — product showing discount but not given on bill

Address: Ambala, Haryana, 133001

Please check i purchased baby frock worth rs 299/- having 50% discount on 15.08.17 but when i saw on bill no discount given and when i go to vishal mega mart on 16.08.17 they said its by mistake. I purchase one more frock of same dicount that was given and mention on bill. It means we have to cross verify every thing when we puchase from mega store. I think its a brand store but for this type of things i dont think its a brand name.. We purchased from vishal mega mart for brand name but its not good practise for a brand name. Please resolve and provide 50% discount on my baby frock.