False sale items

On the 20th i visited Jetmart in Maake Plaza. I bought items from the pile of dirty sale items which promised a guaranteed 75% off further reduction from the sale price. When i got to the till, the items scanned at original price ( not even the old sale price). The cashier claimed thats how it is and she called supervisor to manually guess the discount. The store manually reduces items at 50% off the original price. I really feel cheated and they the company is cheating the poorest comunity because they dont deliver what is advertised and the poeple in maake majority are not educated. I will take this furthet to consumer protection should i not hear a response. I also want my bought items to be corrected at the promised 75% off from the sale price and not original price. The clothes are dirty and really deserve to be cleared at a redicously low price. Thank you