Shocking service both with the call center and stores, as well as other service issues

I have been with MTN for several years, and until recently had always experienced a good level of service. Sadly, however, this is no longer the case! I firstly started experiencing some serious issues with data being depleted at an astounding rate. I went from using 2G of data a month, to having to buy 1G a week. This made no sense to me, as I had actually started using my device far less. Upon calling the call center to try find out why this was happening, I was told that it was because I was using Facebook and Instagram, and becuase of the I Phone software upgrade which I hadn't done (with my previous I Phone I never did an upgrade and never had these issues). I said that this excuse was not possible, as of late I hardly used those. But they insisted this was the reason. I therefore made a point not to use either Facebook or Instagram, yet my data continued to deplete just as quickly. Before this started happening, I used to access Facebook and would post a lot, yet my 2G data lasted a month, why then all of sudden when I started using it far less was my data started going so quickly? I tried to go the two stores at The Glen to see if I could get help. But at the first store they only have 1 technical person who on the one day I went there was assisting a client for such a long time that I had to leave, and on the second time I went there wasn't even there. I tried to then go to the other store at The Glen, but no manager was available, and was told by the assistant manager that I needed to drive to head office to resolve this issue. I wasn't prepared to do that, so instead I now use a Cell C WiFi instead. Clearly my business is of no importance to MTN, so I will rather support another service provider. The second problem that's been happening for a while is that sometimes I cant make a call as apparently I don't have airtime, when in actual fact I do. I need to wait 24 hours before my airtime magically reappears. When phoning the useless call center, I was told it was because I had an internet sessions open, which is utter nonsense as I did not. I was told to switch off the device for 5 minutes, and when I put it on again my airtime would be there. Obviously that wasn't the case, and the airtime only returned the next day. What happens if I have an emergency and need to call out, shall I tell my emergency to wait 24 hours until my airtime returns? The third problem that is also happening is that people are leaving me voice messages, I get a text stating I have voice messages, but when calling 100 to hear them, it says I have none. Once again I have to call the call center to get to speak to a rude call center agent named Vaneshie, who rudely tells me a few things after I tell he everything that's happening of late. Some of the things she told me was that I'm not managing my device correctly, and that clearly there's no data issues as she feels that matter was resolved, among other things. I have actually had it with MTN. Its disgusting that clients get treated in this manner, when although I may be a small fish in the sea in comparison to other clients, I do still spend a decent amount of money every month between airtime and data. Also bearing in mind my husband and daughters are all on MTN. If I do not get any proper resolutions to all the above issues, I will be sure to move all of us over to another service provider, and taking this matter to social media.