Unhappy smartshopper

Today at Pick 'n Pay Trade Route Mall, I purchased 3 x Dr Hanz soft meats in 830g tins which was on special at R22, 99 each. The cashier scanned all my groceries so I paid and before leaving I checked my till slip. Upon checking I noticed that I was charged four times for the dogfood so I went and showed the cashier, Sebongile. She, in turn, took it to her Supervisor who assured me I only paid for 3 tins and the fourth amount I paid for was other dogfood (it did not reflect as Dr Hanz but the same amount was charged) . I did purchase dog pellets which was R62,99 which was showing on my tillslip. She then further dismissed me. I don't appreciate being made like I don't know what I'm talking about and being dismissed. I left the shop very dissapointed cos I knew they wouldn't escalate it further. I am a regular at Pick and Pay but would not be returning to Trade Route Mall's Pnp as customers are not being heard there. It's January and we are all budgeting our daily spend and it's wrong for people to ***** from us.