Disappearing data & no service.

Last week of January & first week of February, i apparently used 10Gigs of data - mind you i connect to wifi at work (from 07:30 - 17:00). Then in the second week of February my sim stops working (no service/connection) and i can't pick a network operator. I call the call center, and they say i need to buy a new sim and not RICA it. Why is it that i am the one now that is struggling to get connection, i bought a cell c sim - as soon as it has problems, why should i get another one? what gives me the idea i won't have the same problem? lets say i decide this is just not customer centric and i want to port to another network - i need to go to a cell c store and it takes 48 hours before they can port my number.

How on earth is this the correct manner to treat a customer - someone you hope will advocate for your brand???