Terrible service or no service actually

Why can't I get through to the callcentre? I have been trying for the last 3 days and have been holding for about 40 minutes at a time. No answer or 20 minutes into the call ( while holding ) the call just drops. Also, doesn't matter when I call you 8AM or 10PM the system always notifies that there is a high volume of calls. I can't believe that. I have sent you a PVT message and if you still want me as a customer you will resolve my issue asap otherwise I will be cancelling my contracts with you and moving somewhere else where I (the customer) will be looked after. What is most shocking though, is the fact that the only department I can get through to is the sales department. SO the department that makes you money is functioning correctly, but the existing customers are not being looked after? This is utter ******* service.