CLOSING BEFORE TIME

yesterday I went to an MTN store to make a payment in Wooderboom. It was 10 minutes before 18:00. when I got there, the security blocked the door and told me that the store has closed, I tried to plead with him, I told him that it is not 18:00 yet but he told me it is an instruction. when I try to reach to Mtn personnel, they told me that they have closed their cash register, I told them I am not going to use cash, I will only use my debit card, it was not enough as I was shouted at and the door was slammed on my face by the security guy. I was left embarrassed and humiliated, begging to do business with Mtn within time frames prescribed by themselves. to me it was very unprofessional and if they continue to be like this, they will lose so many costumers to sister net work. my Mtn number is ***.