There's a problem with MyAccount. The incident is being worked on and you can track it on the Service Status (Websites) page.
The current report says "We’re aware that some customers are currently unable to access My Account, we’d like to apologise and assure you we're working to restore service ASAP"
...the MyAccount issue hasn't been cleared yet. The latest from Service Status at the time of posting is:
Latest update, 3PM 18th August:
We’d like to apologise and assure you we're working to restore service as soon as possible.
Just track it on the Service Status (Websites) page and when the incident is cleared to allow you full access to MyAccount then the Service Status report will be cleared.
Hi TominLondon, your problem should have cleared now as the incident is closed. If not please let us know.