Interesting that since I am on Infinity 2, and just renewed my contract a month ago that I am now only getting the same speed as Infinity 1 users. Seems as compensation I was advised that my BT Cloud storage would be doubled. Received a follow up email today saying that storage had now been increased but seems I still only have 500GB. Thought I would phone to ask where the increase was and have been advised that this will not be implemented until 1st January next year. Shame the email they sent out does not explain all this. Not great publicity if you ask me.
I was in exactly the same position: just renewed the Infinity 2 contract a few weeks before the email arrived.
However, my extra Cloud storage appeared almost immediately after clicking the link in the email. Others in this thread have also received the doubling already too, such as Zombie's post on this thread.