I have the same issue - called up on Saturday evening and confirmed the upgrade on a deal for 12 months and the channels have not been activated yet. When I call again the automated message says that my upgrade is in process.
If the automated system is advising of "upgrade in progress", that's probably the answer. In-case there's a problem with the amendment (given that it's now been longer than the usual 24-48 hours), I'd be tempted to speak to a C/S agent on 150 and make sure.
Otherwise, just make sure that you're checking the right channels (SD/HD) as per my previous post.
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