My line is always soft locked

For several months, my Vodacom line gets soft locked. I don't use data, I have wifi, and even worse, they don't notify me. I woke up this morning and my line immediately got soft locked with no notification. This has happened so many times and my cellular data is always off. Everytime I call the call centre, they inform me to increase my limit and buy more data. This must be a strategy of some sort to increase their revenue. Not to mention that they claim to never be at fault and will never compensate for their theft!