unlocking 3510

The number is - 350843805416715
Ireland - Eircell (although it's now run by vodafone)
Nokia 3510

I got a code from the auto generator and tried to use it and it failed. I've since tried again, and it's saying "cannot undo restriction" Please tell me what to do to unblock this phone as I want to give it to my father-in-law who is in the UK.

I'd be really grateful for any help. Thanks.

Edited to again ask for help. Even if it's to say that I've permanently blocked the phone from being unlocked because I tried to put the code in more than once. It was only after I did this that I noticed the disclaimer. Please, please help.