What Customer Service?

So I wanted to go on the monthly billing plan to pay my municipal taxes. But after completing the forms and mailing in a void check, I'm still on the six times a year system. No problem to switch it, right? Wrong. For the past two days, the one phone number provided to call customer service has had a busy signal: there's no way to leave a message or information about how to do it online. Nice, very nice…..