How to complain about problems with your gas, electricity, water, telephone, council tax, broadband and similar bills and bank charges

How should you complain about problems with your gas, electricity, telephone service, council tax, broadband and other services?
I rarely complain. Mostly I am too busy and cannot be bothered. If I get upset about some poor service or a billing error or whatever, I try to get it sorted but the laws of negative returns often [...]