MTN Store closed at 17:40 instead of 18:00

I went to an MTN Store at Westgate yesterday after seeing that they close at 18:00. I arrived around 17:30 & the MTN store close to Game was already closed. I then went to the other store just next to Cell C & they had already closed, the 2 ladies were just chatting to each other together with a security guard. I stood on the door & they signaled that they are closed, I signaled that it was NOT 18:00 yet. The security guard came to the door & advised me that they are doing stock-take. I then asked him why is there NO NOTE on the door advising that a stock-take will be in progress on the day. He then closed the door in front of me. I stood there in disbelief & he came back again. I asked him if Head-Office is aware that they are closing early or if the Manager is available, he said the Manager is not available. I told him that I will take it up with their Head-Office & the ladies boldly said that I should do so. I did not expect that I would get this kind of service from a private company like MTN, we usually get this treatment in government institutions. I was very disappointed by the way this was handled.