Coupon not given

On Saturday 30th May I went to Pick n Pay Pineridge to do my monthly shop, I noted that there were mixed frozen veggies with a R10 off coupon. upon getting to the till to pay I noted that my veggies had been stuck in the bag and my coupon not given to be taken off my bill. I then had to search through my groceries to pull out the veggies and the cashier said it was because she could not pull the coupon off that's why she had not given it to me. She then proceeded to get her packer to go get another packet of veggies so she could get the coupon off that one. if I had not spotted this I would not have received my R10 off. I would like to note that the lady that actually rang me up was an elder Indian lady and I was not happy with her attitude at all. My shop was over R3000.00 so maybe R10 off doesn't seem like a lot of money but it is the principle of the matter.