When my data cap was finished, I followed the instructions on their website to top-up my account. After a day, the amount still didn't reflect, so I called to find out why. Apparently, my account cannot be topped up in that way. So now they have my money, but say that they can't give it back. I went through the steps on their website, so see if I missed anything, but no. At no stage when instructing their clients to make a payment does it warn that certain types of accounts can't be topped up.
Very clever. Make it as difficult as possible for the client to get their money back, maybe some of them will give up and let you keep it.
Sounds criminal to me.