FNB and Vodacom not taking responsibility for lost data

I bought data (Vodacom) for a family member via my FNB account - this was never loaded & FNB do not take responsibility for the matter. How do I take the matter further - it seems as though both service providers are happy to take one's money but responsibility, not too much! Someone has my money & I would like it back. FNB report: "After investigating with the network operator, their findings were:

? That the Data was topped up successfully."