Airtime used on Data contract

I have a data contract that is being used on a WiFi modem.

I had airtime available on it. When my data ran out, I wanted to topup from the available airtime. When looking at the balances, my airtime was zero.

When I called the call centre, I was told that because my data ran out, my airtime was used in stead. So I was using approx R2.00 for every 1 meg, whereas I could have bought 2 gigs for less than R100.

I want my airtime back !!!