deducting airtime even when data is available

this has been happening over a few months now but this past month has gotten really bad cause of my billing charges. I have contacted them a number of times but all they say is they will escalate it, still nothing has been done. currently my bill set for the end of sep is over R1000. problem is I always have enough data and minutes, and now im forced to buy airtime just so the network can use that instead of data plz sort this out soon. my package is for R240, my bill for aug is R307, I want the difference back in my bank account soon, as this is defiantly a network problem