This is how you need to do it
get a replacement via the Lost process which is on this link
You can then bar your SIM and/or handset.
A new replacement SIM will be sent to you. which will have the same number and any credit put on your account once activated
There is nothing you can do sorry, the new sim would be a new account. Any existing credit you had on the lost sim will still be there once you receive the replacement. :-( you could try emailing an agent explaining what you've done and hope for a good will gesture at best, but GG do not offer refunds unless they were at fault :-(
I order both : new Sim and the replace one . ^^! And I top up 10£ for the new one instead the replace one . What can I do now? Because the lost one I've got 10£ already