vodacom not assisting with airtime missing

Good morning. For the past couple of months I noticed how my airtime and data just disappears. I don't have automatic updates on my phone, I update my apps at work via our wifi, I close all my recent apps constantly after using them. I called in red passivity that I need someone up investigate this matter as I feel vodacom is *****ing / hijacking my airtime, of which I was told that there is no such department who can do that. Vodacom does not want to take responsibility when a fault is on their side. I've been having endless problems to an extent where I don't even answer the phone if vodacom calls because their service sucks and their customer service call center agents are not trained and not customer focused as they should be. Back to my point. My airtime is just disappearing and vodacom needs to give it back. I buy a lot of airtime each month and data and use it wisely but the past few months my airtime goes missing and my data is just depleted before I even realize. On Wednesday at 9am my airtime balance was R308 and my data over 1Gig data. As of yesterday 11pm it was gone. I only downloaded 2 episodes and they were 300mb and 250mb each respectively.