Lack of customer service with AT&T

Hello. My complaint has to do with AT&T's lack of customer service/billing. When I call customer service to ask a question, I get put on hold, and half the time, I am either just left on hold, or the call gets disconnected. This is very frustrating, especially when I have past due amount to be paid, and need to make arrangements to pay it before they shut off my service for non-payment. I cannot afford to lose service, or am not able to switch to a company with real customer service.