How to unlock an orange iphone 4?

I have just bought an iphone 4 from ebay. It was on an orange network. When I inserted my 02 sim it will not work and orange say they can't help. Any ideas please?

Call up Orange and request a PUK code. This may cost a bit, but it's not usually much and it's the safest and best way to do it.

Either call orange up and ask for a unlock code or use an orange sim card