I would like to upgrade my SIM plan to increase the data. Previous, I found it could be done by online customer portal but I cannot switch my plan anymore now. When I pressed the change plan button, it will direct you to BT boardband page and ask you if you have BT boardband which is irrelevant .Could anyone help?
It's not irrelevant as you get discount on your BT mobile bill for being a BT broadband customer.
If you are a BT customer with a login to MyBT then login before making any changes otherwise just answer 'No'
From some other posts it appears BT are suggesting you love to EE and not renewing with BT. That would seem to be the current way forward