Updating Mobile Phone Number

[S.A McDonald]

I'm trying to update my phone number from an older redundant phone number under my security settings to a new current phone number.

When attempting to do this it asks you to confirm a code sent to the old phone number as well as the new phone number as part of the security check.

I have no way of checking the previous phone number for a code as it has been deactivated some years ago and is not retrievable.

How does one update their phone number in this situation please?

[Keith Watford]

Contact service desk