speak to supervisor or higher level in charge, of technical department my calls are being disconected or not even connected

It's been over 3 months we have been complaining about the sames thing, calls being dropped or clients getting message please enter your voicemail password" instead of getting our greeting. Every time I call to fix one thing they mess up another. Just yesterday we called again with the same issue about clients complaining that our line only rang once and called was then dropped. Mary the person who got our call at ring central now disconnected all our greetings and only 2 phones ring. I am ready to throw the ropes and leave them after almost 10 years.