Lesson learned from buying a phone on contract

I bought a phone on contract last month at Telkom store (Mall of Africa) and Bongy Mcunu assisted me. I went to the store after work around 6pm. I explained to her that I am buying the phone for my younger brother and can she set a limit on the data usage so that i do not get shocked by the bill. I further asked what he will be entitled to use in April to ensure that I do pay high amounts outside the contract amount. She told me that all the data bundles will be active (including the 10GB promotional data) in March. I received my bill on the 9th of May and I got the shock of my life. I went to the Telkom store at Fourways mall and they told me to go to Mall of africa because I bought the phone there. They also told me that there is a R500 spending limit they allocate to customers and its active in the first month of purchase, this was the first time I hear of such a thing. I went to Telkom store at Mall of africa and Bongy did not want to speak to me after being called by her fellow colleagues who explained my situation to her. Her colleague showed me some tick form I sign and said it shows that Bongy explained everything to me, I told her colleague that Bongy told me to just tick off everything thing because its not the first time I buy something on contract from their store. She did not explain anything to me regarding this mysterious R500 that Telkom gives you. I was at the store for almost 3 hours as she was refusing to come talk to me, she was hiding at the back of the stock. The manager logged my case and but I am very unhappy with how things were handled by Bongy, you rush to makes sales but can't own up to your mistakes at other people's expenses.