Hello, I’m Nathan, and I’ll be assisting you today. My livelihood depends on your positive feedback, so your satisfaction is my highest priority.
Sorry to hear you’re having trouble.
Can you tell me what model pbx system you have?
In the meantime, for your ringer, try just pressing the volume up (up) button on the phone, while not on a call (standby mode).
If that doesn't do it, wait until the phone is ringing, and then press vol up as it is ringing, until you get to the desired level.