What are you actually saying in your complaint? 'O2 are selling the new iPhone too expensive for my liking'?
The 'unlimited data' and charging for tethering is pretty annoying, but to be fair you could use a massive amounts of bandwidth downloading to your computer, and when they first promised 'unlimited data' it was clearly just for use within the iPhone, it's still reasonable to assume that’s what they mean.
I'm annoyed/disappointed by it, but I'm not sure it's reasonable grounds to complain to ofcomm?
Im sorry but I disagree with you on this.
One of the main selling points for the iphone was the unlimited data package, as far as I was concerned.
I see the new unreasonable charges of £15 for 3 gig on top of whatever your monthly charges may have a point with ofcom regarding the misleading wording of the original "unlimited" data contract.
It is o2 simply misleading the customer regarding the terms of a unlimited data contract.
As far as your point regarding the massive potential for downloading ... o2 have always had ( and still do have )a fair usage policy so that could limit any excessive downloading over a tethered device.. simples