Hope I'm not speaking out of turn, but your post at message 3 makes me wonder if you're confusing your BT Broadband and bt.com (MyBT) details. SmartTalk does not require your BT BB details (email address and password) at all. If you click MyBT at the top of this page, the section at top right gives the choice to Log in or sign up; these are the details that SmartTalk requires. You will have to sign up if you haven't done so already; your BT account number shown on your bills in the form AB 1234 5678 will be required for that.
I have been trying to make sure that sign in wa MYBT
once logged in go to my services and on bottom left under manage my services can you see smattalk?
then I would try online chat and see if they can sort it out
you have been trying from a pc to access MYBT just you keep posting from your mobile