assistance not provided.

I accidentally purchased data bundle from my FNB App for my cousin today but then i realised that the cell number i used is an old number that is not in her possession any longer *** R249 4GB data). I tried the Vodacom customer care but the TOBI selection does not accommodate for this query. I wend to your Vodacom branch in Constantia Village but they refused to help me and told me to go to FNB I wen to FNB and they told me the information has been send to Vodacom and they can't help me wither.. Please advise how I can cancel this purchase. my purchase reference number is VODS2W4H1D3H. I need to cancel this purchase. Thank you my cell phone is ***