I was just looking at upgrade options on My BT but when I click on the button to show me my offeers I am told I don't have a landline with BT and to call to have my line transfered. I'm on FTTH Infinity 2 and have been for quite a few years now and not had troubles upgrading in the past from Infinity 1 to 2.
Has anyone else had similar issues?
If you have FTTH/FTTP then you should phone dedicated team 08005874787. To get help
If you have FTTP without a copper phone line it will be a VOIP number, your sister may have a copper voice line.
There are very few FTTP providers in any case, none of the mainstream ISPs offer it.