Vodacom *****s my airtime every time

I am very disappointed with Vodacom. I bought R70 airtime on Saturday and my mobile data was switched off all weekend because I have WiFi at home. When I wanted to purchase mobile data today, my airtime was gone. This is not the first this has happened. When I have data, my airtime seems to be the first to go. When I don't have airtime, I use about 10 megabytes of data a day. My phone doesn't use any background data because I restrict that. So if Vodacom wants to say that that may be the reason for my airtime getting finished, it's not the case. I know what I am doing. I want to be re-imbursed for this. It's not fair that they keep taking from me and nothing gets done about it. I have been using Vodacom for more than 20 years but I won't recommend it to anybody. I tell my friends and family how Vodacom *****s your airtime. So disappointed with Vodacom.