Weird Call to undefined method which is defined at the User Model

I have added this method to my User Model:

public function userType($type)
    {
        switch($type){
            case 7;
                return "Brand owner";
                break;
            case 9;
                return "Shop owner";
                break;
            default:
                return "undefined";
        }
    }

And then on my index.blade.php where I retrieve all the current users, I added this:

@foreach($users as $user)
<td>{{ $user->userType($user->member_type) }}</td>
@endforeach

But I get this error:

Call to undefined method App\Models\User::userType()

So what on earth is going wrong here?!