Operating hours

I upgraded through the head office. This was great; friendly service and very quick delivery. But activating my new SIM so that I can actually use the new phone has been an absolute nightmare. My phone was delivered towards the end of last week. Unfortunately I was late to call the Call Centre so that I could activate the SIM. The answering service at the Call Centre stated that their operating hours are Monday to Friday 8am and 5pm and to try again then. So I went into the store at Hemingways, East London on Saturday and was told that I could not activate my SIM over the weekend even in store. So I called the Call Centre today (Monday) at 16.15 and no one answered for the 45 minutes that I tried to get through. I just want someone to get back to me to tell me when and how I can activate my SIM. I work Monday to Friday 8 am to 4pm. But it does not help me if the call centre actually closes at 4pm. I then dont see another time that I could possible activate the SIM?????? Please, there must be a solution!