Disrespectful teller

I'm writing this email with so much disappointment. I went to Engen garage in Nimrod Park Vulstasie Monument road 73 Kempton Park on Saturday around 13:34 to fill up my tank and I then realized that I'm going to need data I then went inside and bought a Telkom data from a teller by the name Jackson. I then went home when I get home while trying to load the data I realized that Jackson gave me the wrong data. I then drove back to the garage and told Jackson that he sold me the wrong data he then insisted that I said MTN I then told him that no I can never say MTN because I don't even use MTN I use Vodacom and Telkom I stood there for almost 30 minutes trying to knock some sense into his head, I got so irritate because he was now patronizing me by disrespecting me he even told me that I'm very disrespectful and he knows my kind. I was shocked that a "manger" can speak like that with a customer because apparently his the manager I've asked to speak to the manager and he insisted that his the manager I'm honestly irritate by this because I've wasted my petrol and I didn't even get my data too. He told me that I should leave the data and he will sell it for me I should go and once someone comes to buy data he will sell it for me I told him that but why can't you acknowledge that you were wrong and you made a mistake all I want is a Telkom data and that's it he treated me as if I'm doing him a favor he was very rude and very unprofessional I'm honestly very disappointed in his behavior such a small thing that he could have been handled with professionalism he decided to make it personal by even telling me that I don't have manners how do one tell a customer that they don't have manners me demanding to be reimbursed was wrong, all I ever wanted is for him to acknowledge his mistake and do the right thing so now he was doing some kind of reverse psychology as if I don't know what I was looking for I'm very much irritate and I don't think I'll ever pore my petrol in that garage. And mind you I left without being helped I even left this data there I'm sure he uses MTN he wanted it for himself