Kfc refuse refund

On the 26 of June 2024 I purchased a 10 piece family meal and a bottle of water that came to R275. 80. On payment I zapper on the counter and the purchase went through on my side but the cashier informed me after that it doesn't work. I said ok I'll swipe but if the payment went through I'm coming back to confirm money went through twice. I went to the Manger on duty Nolupho, she was such a dear and tried her best. With update Nolupho send me a screenshot of the treasurer's email stating it went through once from on there side and I should go to my bank. I went to my bank, they confirmed process took place on the 27 and the 29 of June and they still refuse for my refund given the statement, proof and bank confirmation. It's been 3 weeks still no communication. I called this morning asking the manager on duty to contact me because apparently Nolupho went to the hospital meaning no one is busy with this case. Can I sue them? This is the point they pushing me to.