Data disappeared and bad customer service not knowing to explain

My three gig just disappeared in a minute. I went and do internet banking after when I check my app it was 9.8gig after a minute was 6.7. What happen. I called your call cente told me there is no history but my data is gone. They can’t answer that. And the same day my airtime disappeared on undelivered message all to be told it happens is normal at vodacom. Is this how I’m trapped in a contract that I can’t use my data will just disappear and get stupid call center to tell me there is no history under your contact. I must just accept From **********