Vodacom takes money for no service rendered?

I switched to prepaid so when my data ran out the message suggested I dial *123# to add more data as out of bundle is expensive. I did that 3 times over a period of 2 days and each time money was deducted from my available airtime but no data was received and out of bundle charge stacked up. I contacted customer care and they said they can see the purchases but no data was loaded so they will refund the money and the excess data charges. This has still not been done. This money should be refunded as I will not be held liable for errors on your system that you did not even pick up. It cannot be that hard to put a check in to see if these transactions are successful.