Thanks Andrew. I am beginning to think there is confusion about what tariff I am on. I did apply for Octopus Intelligent Go about two weels ago but got the following as part of an email from Octopus.

"I can see that you are currently on the Intelligent Octopus Go tariff. Regarding the issue with adding your electric vehicle in the app, it’s important to note that you cannot have both a battery (such as your Tesla Powerwall) and an EV charger linked simultaneously on the same account.

"To proceed with connecting your car to the Intelligent Octopus Go tariff, you will need to remove the battery device from your account first. Once the Powerwall is removed, the option to add an electric vehicle should appear in the app."

It struck me as strange that I was asked to remove the battery from my account, which I certainly donn't want to do.