Organisation heroku email used for personal heroku app

When running:

git push git@heroku.com:.git $CIRCLE_SHA1:refs/heads/master

As part of my deployment commands

Circle CI seems to be using the Heroku creds that belong to an organisation I work for, I only assume this because I get this error:

git push git@heroku.com:myherokuapp.git $CIRCLE_SHA1:refs/heads/master

Warning: Permanently added 'heroku.com,50.19.85.132' (RSA) to the list of known hosts.

 !  Your account not@myherokuemail.com does not have access to myherokuapp.
 !  
 !  SSH Key Fingerprint: A SSH Fingerprint

fatal: Could not read from remote repository.

You can change this in the project’s settings. You can reach the project settings by clicking the gear icon in your branch picker. Scroll down in the settings to the Continuous Deployment section and you’ll see Heroku Deployment.

A possible shortcut:
Github project:
https://circleci.com/gh/[$OrgName]/ [$ProjectName]/edit#heroku

Bitbucket project:
https://circleci.com/bb/[$OrgName]/ [$ProjectName]/edit#heroku