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.
You can use the same model system for replacment. However this is a very old model (16 year)l so they are difficult to find. You can sometimes get them on ebay, but be sure you buy a matching pair.
You cannot buy just a handset, you have to replace both the handset and the base, as they are linked together at the factory - you cannot just program a new handset to the existing base station.
This is the current iteration of a cordless model that can integrate with your existing pbx: http://amzn.to/1NaCSFZ