Telkom data disappearing

I have had a contract with telkom mobile for over a year now. Yesterday after they recharged my mothly data. It all disappeared. This started last week when i bought 250 mb of data twice and i never used it but it also just disappeared. This all started last month after all this time i have been with telkom. I feel this is day light ******* as when you calk their call centre all you get is a voice prompt. They sent me an sms saying i have 505 mb and in 3 minutes time sent me another one saying i have 200mb. How can 305mb disappear in 3 minutes. I have been a loyal customer and dont deserve to be treated like this. I never changed any settings on my phone for them ti reply on Facebook saying my background apps are using my data. Why only now? After all these months? I need my data back or i will cancel this whole contract and debit orders. They should have the decency ti aleast call me instead of hiding behind facebook. I have heard people talking about the bad service they got from telkim and defended them but now its happining to me. I want my data back or i will block your debit orders