the name is already in use

I have taken over looking after a Yii2 app. At the moment, I am struggling to get it working on my laptop in a dev environment, it works perfectly on the web (well not with this error anyway). On the front page there is a login page which checks you are an authenticated user and loads a token into a cookie which then enables other pages to load.

When I try and login, it comes up with an error message saying "cannot use common\models\base\user as user because the name is already in use" This is loaded in common\models\organisation.php and used in the common\models\loginform

things I have tried so far:

changed the line - use common\models\base\user to use common\models\base\user as tUser and then on the loginform changed the line $this->_user = User::findByEmail($this->email) to $this->_user = tUser::findByEmail($this->email)

but that comes up with a message saying "common\models\tUser not found"

taken the line "use common\models\base\user" out of common\models\organisation.php and put it in common\models\loginform,php

but that comes up with a message saying "call to undefined method common\models\base\user::findByEmailForBusiness"

that function is actually in common\models\user to then I changed the line in loginform to "use common\models\user" then I get the error message "trying to get property of non-object" again

I tried adding both lines "use common\models\base\user" and "use common\models\user" to loginform but then I get "cannot use common\models\base\user as user because the name is already in use" again

I’ve looked for where else User might be declared but can’t find it anywhere and I’m struggling to know what to try next.

Any ideas?