I�ve got no idea why they don�t offer the 100 Mbps guarantee but I wouldn�t worry too much, as it still appears to be the same 330/50 product. You�re definitely on Huawei gpon infrastructure as your line can support up to 1 Gig though the higher half gig and 1 gig services are in very limited areas at present.
I should also add: 100 Mbps speed guarantee or not, if your speeds fall considerably during peak times (say down to 150 Mbps on the 330/50 service) then BT may put you on a different virtual path at the exchange (SVLAN) after you've gone through the usual troubleshooting steps. This has already happened with 1 or 2 other users on Bt Retail though its a long (and often painful!) path. Example
here.
Edited by deleted (Mon 18-Feb-19 13:09:53)