I was on Superfast Fibre 1 Unlimited or whatever it's called and quite happily got 48-50 Mbps downloads and 9-11 Mbps uploads.
When I changed my mobile etc. they "upgraded" me to Superfast Fibre 2 Unlimited - now a couple of days later I get between 1 Mbps to 30 Mbps downloads and 15-20 Mbps uploads.
Please tell me this is just down to the recent change taking a while to settle in and I'll get my "guaranteed"56 Mbps or higher