FreePBX asterisk VoIP server and Mitel/Aastra IPPhone Configuration

Looking for an experienced contractor to update configuration on our VOIP environment (a dozen or so phones). Currently using PiaF / FreePBX but happy to change to another distro if needed. Most phone are Mitel/Aastra 6739i and plus a couple cheaper aastra and a polycom conf phone. Key Issues / Targets: 1. Hot-desking - Configuration to allow for user speeddials to move with users as they log into their phones. 2. Call barging is not working properly at the moment. 3. Peering to another VOIP server 4. Bring our old server up to scratch. 5. A few more minor ones that I can't remember right now As the aastra phones are currently using the aastra XML login scripts experience on these handsets will be ideal. However will consider ditching the XML and use server-side endpoint managers if it can achieve the same outcome. I suspect a big server refresh and the addition of some commercial FreePBX packages will solve all my problems but I just don't have the time anymore. Site is located in Sydney, Australia. Remote access will be provided.