AppId is over the quota
Well, I rang Xbox Live customer support again and they told me that in coopertation with New Zealand authorities they are enforcing a new policy that under 18s cannot download content. They could not specifically tell me who, however they will be emailing me in 48 hours when they have this information.
It seems that some new law must have been passed, but I haven't heard anything about it. I told them that not all content is unsuitable for under 18s and that there will be a huge backlash from Xbox Live users because lots of them are under 18.
I urge you to ring up Xbox support, cancel your xbox live subscription and tell them why to boycot this new barbaric law. They will be forced to do something about this if enough people cancel. I will post details of the authority once I receive my email. Spread the word!