Refuse to honor prize even though they know they are wrong

In January 2016 the network was off in my area. I missed 3 calls from Cell C in connection with a competition I had entered for 100k. When the network came back online, I saw the missed calls and immediately started contacting the people from Cell C. Their response? Because I missed the calls, I was not eligible to claim the prize. Try explaining to them that I missed the calls because of their network outage? I must provide proof. I have a website where I load screen shots every time the network is off. 100's of hours of downtime. But that is not proof enough apparently. Cell C just refuses to do the right thing. What a horrible horrible company.