The worst call centre ever

I have no idea why they have a call centre, it is the ****tiest I have ever experienced even the government call centre is even better. No answer for over 30min and it automatically disconnect. They keep sending me email about an unpaid bill even when you have paid the bill using their ref number. I wonder if they put those ref numbers on the invoices for fun. I wish they was a negative zero star, I would have given them that.