switch in factory class

I have a factory class that decides to which bank service should instantiated based on input so I created it with switch in factory class like this:

class BankFactory
{
    public static function build($iban)
    {
        switch ($iban){
            case "123":
                return new BankXService();
            case "456":
                return new BankYService();
        }
    }
}

But every time that I want to add a bank service switch case is longer and longer.

Is there any better design pattern for this task?