Food *****s Market Poor Service

They have a special combo of 1kg Tomato, 1kg Carrots, 1 pre-pack lettuce for R49.99 and then you get 3 Avo's free, I took the combo as it is packed at the entrance of the shop and continue with my shopping. When I arrive at the till, the cashier put everything through and I paid what I owe them. When I received my till slip, I checked and saw that they did not put it through as a combo and charged me R90.80 for all the products that was included in the combo. I returned the combo and asked for my money back. This happened although the advertise on the radio as well about the great combo, This is not the first time this happened. I urge people who buy from Food *****s Market to check their Till slips to make sure it is correct. I have supporting photo's of this.