Wrongfully accused - Defamation of character

I am a frequent shopper at Pick 'n Pay at the Kyalami on Main branch and this past week Sunday was the most embarrassing day that I have shopped at any store. I went into the store to check what specials were on and after purchasing and paying for three items I was stopped by the security guard asking to search me. I did refuse as this was my right for them to provide evidence first. I asked the security guard, together with her colleague and the store manageress to provide me with the video footage before they can do a search on me of which they said that they would provide. Both security guards seem to be adamant, through lack of training or lack of vision that I was the perpetrator. They started to speak in their vernacular which I do not understand and this started to frustrate me even further. I asked what would be the logic of me purchasing three items and *****ing a Berocca effervescent of which I was accused for. This entire ordeal happened at the front of the store in full view of all the other customers. As I begun to get more frustrated as they were stalling to show me video footage and speaking in their vernacular, I just emptied out my pockets and asked them to refund me for three items that were purchased as I do not intend to purchase from Pick 'n Pay ever again as this was the most embarrassing shopping experience for me. After they had apologised, I stilled requested to be shown the video footage that had made them to make this wrongful accusation which caused me to be defamed. The manageress just blatantly rep**** that I cannot view it. I told them that a proper security system should be in place and they should not be just waiting at the door wrongfully accusing good spending customers. I did write an email to Pick 'n Pay 'customer care' on Sunday 25/02/2018 on the exact day of the incident, but needless to say they don't 'care' as I have not even received a reply from them. Pick 'n Pay should invest in better personnel or proper training to make hard working, good spending customers feel better about their shopping experience and not be victimised because of negligence of their employees. I can't believe that I have used so much of my hard earned money at that store and be treated with such disgust.