I have the same problem, I got onto live chat with three Ireland tonight. Took them 15 minutes to tell me nothing they could do as the top up gone through, I should be more careful when topping up. I will not get a refund.
The worst is, if you look the topic up in goggle and go into the results you see people have in the past been refunded by three for accidenty topping up the wrong number if they did so by a bank card.
