Post office not delivering mail, and can't eplain

Since last year, I have been receiving mail in drips and drabs. Most mail arrive between 8 - 16 weeks late. Then important packages gets returned to sender, even before I receive slips.<br> <br> I logged a complaint with the post office in August 2015. As to date I have not received any explanation to the problem, no improvement on service, and no explanation as to why we need to pay for a service that is not being rendered.