Can I change my tariff on my contract for Orange?

I recently had my blackberry phone stolen and since I do not have insurance, had to buy a new phone (iphone 5)

I got a replacement sim card but the internet doesn't work on my new phone so can I change my blackberry internet to iphone internet even though I'm on contract?

First of all try resetting the network settings on the iphone by going to settings - General - Reset, then tap on Reset Network Settings. This will delete all network settings, returning them to factory defaults.

If this doesn't solve the issue, ring up your network provider and tell them to reset your services to be compatible with iphone. Most providers will change it for free however they will apply same data limit to the new settings.