Complaining customer treated like dirt

I went in the store on 2nd March and bought fruits of about 200 Rand. Between these there were desert peaches. As is usual there, there are no prices on the shelves and one has to go and ask the person at the weighing point for each item's price. I asked about these peaches twice, once the worker who was replenishing the products - who went to the scales and showed me the price of 12.99 R/kg. After I filled a bag with 2 kg of peaches, I asked again both the same worker and the woman doing the weighing and they both confirmed the price of 12.99 R/kg. Arriving home ... realized I have been charged 16.99 R/Kg ! I went back next morning and asked to talk to the store manager. He was there and, when asked how he deals with *****ing he said they do not tolerate any attempt. However when I related the incident - which to me was on a par with *****ing from me - he was very rude and, after a perfunctory discussion with the woman at the weighing station, during which of course she denied any wrong doing, he literally threw 10 R at me and walked away refusing to discuss the matter. I found this very offending and although I used to spend around 1000 R/week there, I WILL NOT GO BACK !!!