unfair treatment

I have been with Vodacom for many years. recently a few guys used my internet sharing. i had no data and vodacom use expensive airtime to fund the data usage. in the pass they use to notify me if my data was finished. in an hour they deducted almost R600 in airtime for data. I phoned them. The gentle gave the monies back to me as a courtecy. However, that same night the cancelledit again. their words was - it just tough. they do not have to explain this to me. they do not have to notify me. NIce!!