AIRTIME disappeared

I always load a 1 gb data bundle once a month. I hardly ever use airtime. For the last few weeks when I google or go into whatsapp it uses my airtime and not my data bundle. I phoned their USELESS 24 / 7 number only for them to put down the phone twice and then finally after holding on for 24 minutes they picked up to be of ZERO assistance. Talking ******* about promotional night time bundles. Mtn is a useless network and I will not recommend anybody ever get an mtn. They are ******* that ***** your money and have ZERO customer service thats why they have a 24 / 7 customer care number because thats how long you are on the phone to try and sort out a problem.