I have had a Monzo account previously (over 12 months ago) and closed it down.
However, I would like to open a new account, but going through the registration process in the app it still recognises my mobile number and says that it is linked to an account and I cannot get past that point in the app.
I was able to get access to the app by clicking ‘I have an account’ and getting a magic link. Then I contacted support (the only accessible part of the app) and asked them if I could reopen
The query was picked up within minutes and the next day I had an account. @dan8030 you might be able to do the same? That said, there is no guarantee Monzo will let you have another account, it depends on circumstances.