airtime missing agian

last night i loaded R55 on my phone, i used R2 worth of airtime and bought 50 mb for R3. before I slept I had R49 airtime. this morning I wake up to my usual monthly allowance of R200 and 100mb but my airtime has disappeared over night. this is a recurring issue with vodacome, this is now the third time it has happened. Vodacome please can you kindly give me back my airtime I am a struggling student and should not have to go through this every 3 months with you