We have finished the game once and have started a new character. The auto levelling does not seem to be working as we are at 2000 experience points and still at level one. Needless to say we are a bit ticked that we can only play the game once. Anything we can do to fix this?

I have seen this before, if you have your old save file with the old character still on your profile the game will base the experience requirements on the level of the old character. The old file will have to be deleted or maybe moved to a different device than the one you are saving the new character on. If that does not work try then also try clearing the system cache.

I deleted my first character (he was a test run/hardcoe run), cleared my cache, cleared all the saves and haven't had a problem with it on any subsequent characters.

It's not a great answer, but it works if you're really itching to go through it again.