Cell C to cannot do a simply change of plan. Be warned, stay away from them

I am a pensioner and had a very basic cell contract with Cell C for the past 6 years - on a month to month basis. Yesterday I received a message from them stating that I have to change my plan. Reluctantly I did so. This morning I had service on my old contract until 9am when it all just switched off - no minutes, not SMS, no whatsapp and no internet. I have made 3 telephone calls with Yvette, the consultant who handled my change and it is now 5 hours later and I STILL have absolutely no service. Why do you have to try and fix something that is not broken. For 6 YEARS i have been quite happy with what I had, but no, Cell C decided to change things and still force me to accept inferior products for a greater price. If my service is not restored by 3pm this afternoon, I will be cancelling my contract completely. I think it is disgusting. I am a pensioner who has not mean of contact with the outside world except with CELL C, which I do not want. Thank heavens I have data on my VODACOM usb which is how I am able to write this complaint. Cell C, wake up, pretty useless service - I am frustrated and disgusted.