Vodacom refusing to help with wrong number transfe

I was transferring R 275 airtime voucher from my FNB account to my friends phone. After the transaction we realised I punched the wrong number for his phone.Called FNB who said the transaction is in the correct amount and cannot refund.WENT to Vodacom customer care Eastgate who point blank refused to even listen to me. How hard is it in case I can proove the transaction to be reversed and sent to the right number?The wrong number is off so the airtime hasnt been used.I should be able to choose who benefits from the sale!Please assist with the situation urgently