>> But: their webshite is abysmal, their customer account admin area limited
Every single mobile operator's website is abysmal. No matter how much time I spend on EE's website I cannot find out how much I am paying, what I am paying for, or how I change any of the 'addons' or whatever they're calling them this week. I can, however, very easily buy more services or "upgrade" to a more expensive tariff.
The awfulness of the websites is deliberate.