Where has all my airtime gone?

I have been a Cell C customer for many years. In 2019 for financial reasons I changed my contract to one with limited airtime, which, although highly restrictive, has been sufficient up till now, with the 'any network' airtime lasting about 2 weeks a month, after which I purchase a 'top-up' which takes me close to the end of the month. All of a sudden, in 2020, with no warning, the same contract airtime lasts 1 day if that (and it's not as if I've been calling the world to wish everyone a happy New Year...). Purchasing of an additional 240 minutes (and according to my calculations that should be 4 hours) of so-called 'any network' airtime has allowed less than half an hour of use, leaving me with no 'any network' airtime until February, and one and a half years to go with this completely useless contract. So airtime which in 2019 which would last me for almost a month, barely lasts 4 days in 2020. Why do I suddenly have so little 'any-network' airtime in 2020, I wondered? Well, according to the call centre at Cell C, this is because Cell C has (unilaterally) decided to split 'any network' airtime into mostly Cell C airtime and a smidgeon of true 'any network' airtime, *****ing me over royally (because presumably, most numbers I seem to call are not cell C numbers - how would I know?) So what can I do to make the people I call change to Cell C so that I can talk to them? ... Actually, why would I even do that i.e. recommend Cell C to anyone after this latest dictatorial move (assuming that what the Cell C call centre agent told me is true...)? I now have more Cell C time than ever, seemingly (- way more than I need and will ever be able to use), and no 'any other network' time, after this completely ridiculous new move by Cell C (obviously intended to cut costs and boost the Cell C profits). Why call it 'any network' airtime if it is really 'x' amount of cell C time with a little 'y' amount of true 'any network' airtime? This is misleading and is in fact, a lie, This is not what I purchased, and it severely depletes my value for money. As a result I will not be recommending Cell C to anyone ever again, and I will be moving to another service provider the second this contract runs out. Lucky for Cell C, they can continue *****ing me over for another 16 months, if we ever get that far, but after that, it's one less customer for them. Not that they care, but anyway.