Vodacom Keeps *****ing

Every time I buy airtime it disappears without me using it,It happens with larger amounts normally but its happening with small amounts too now! And Im ****ed off about it, I had R12 airtime a few minutes ago, I try buy the hourly data and it tells me insufficient funds and shows me I have R8? While I still have active internet bundles and haven't used tha airtime since I punched it in just before trying to use it. Vodacom sucks