bought data for inactive sims, need it transferred to active sims

I'm transferred data to 2 old numbers from my FNB online banking, buying 6GB data so my kids can do school work. I had their names saved and bought, but when they didn't get it I saw it's the old numbers. The sims are inactive, why can't Vodacom just transfer the data to the new sim cards? I don't want the money, they still need to do school work. I know I pressed confirm to buy, but we are all under stress here, why can't you help.