please reconnect my prepaid that has money in it

I have been a MTN contract client since cell phones came into SA. I bought a TOUGH phone last year and a prepaid for when I ride my mountain bike, as my smart phone cant take the punishment. I make sure there is always R100 in it and that I use it once a month to keep it \live". i was out riding and had a problem and tried to use my phone. The sim was invalid.Here I am in the middle of nowhere and stuck. I was furious. |I tried phoning all the help lines which is a joke as you just get cut off"