I am a new customer with Nestar

I am a new customer with Nestar. Little bit dissapointed with their absence customer service. I paid them the money for contract early this month and send them proof of payment. I didnt get any response from my email. What they do now they busy sending payment debits in my account and they cant find payment. Bank has deducted me for insufficient funds. I am trying to call them now they say they are not working today. But what should i do?