An I-Mali gone wrong and can’t be solved .... really?

I sent an I-Mali to the wrong number , I got all digits correct except one 7 that I mistakenly wrote as a 6. After 3 minutes without receiving a voucher pin I immediately called the Call Centre to reverse it and they said there’s nothing they can do. So does that mean that person gets to walk off with my Money? I genuinely don’t believe there’s nothing they can do.