|I would agree with guapo 100% on this.|
You need to find better equipment from a better vendor who supports what they sell. It's rather obvious these guys don't if their advice to all clients with what I would consider a "known issue" with this equipment is "reboot the phone and reboot your router"
They should be fixing the issue.
Regardless, dump them and move on. I wouldn't really recommend Cisco equipment as they gouge on their support packages. They're more than happy to give you great support, providing you supply them with your firstborn male child and the pound of flesh nearest your heart..........
I would do some research and read reviews and look for something that offers both a decent price at the outset as well as reasonable support contracts.
It matters not how straight the gate,
How charged with punishments the scroll,
I am the master of my fate;
I am the captain of my soul.