Panasonic NS100 PBX Troubleshooting

I need an expert who knows the Panasonic KX-NS100 inside out to take over ongoing maintenance and, more urgently, to hunt down stubborn routing problems. At the moment we are plagued by ghost calls, fake trunk activity and sporadic audio drop-outs that confuse users and clog the logs... (Budget: $15 - $25 USD, Jobs: Asterisk PBX, Cisco, Linux, SIP, Technical Support, Telecom, Telecommunications Engineering, VoIP)