Sky Fibre Max Availability

I've moved house recently and ordered Sky Fibre Unlimited which is now active and i'm getting pretty much full 38mb so happy enough with that.

I had however wanted Fibre Max which I was originally told I could have by the online sales people but when I ordered on the phone a bit later on I was told I couldn't have Fibre Max.

Does Fibre Max have different availability to Fibre Unlimited, if so is it a BT reason or a Sky reason? I work from home and move a lot of large files around so faster connection for me would be helpful.

Any ideas?

Sky changed their policy on Fibre Max and only offer it on lines with a guaranteed minimum speed of 57.4 Mbps.

We were refused it even though the BT speed estimate was 58.4 - 77.8.

It must cost them a lot of customers in the 40-60Mbps range.