Hi fenna!
Yes I phoned from England. I have a mobile contract with 3, and on 3 Mobile Phones you get a Skype App (Under 2p per minute to call Canada) so I called with that. If you have a landline, use 1pminute.co.uk. I called Foreign Affairs Canada and then went through the options to get through to Citizenship and Immigration Canada (I think it was 1, 2, 1, 2, 2). Their number is (613) 944-4000. If you call at 13:00 (8AM there), it seems to be the shortest wait time. I waited 4 minutes in the queue before getting through.
**Edit: I was a little unprepared because they asked me loads of security questions and I got a few wrong (I kept saying I paid $1049 when it was $1090, etc.). So make sure you have everything in front of you - if you have a Client ID Number (I didn't), then you're probably better off.