Avaya phone installs

Anyone had any (good) experiences with installation of an Avaya phone system? I'm just wondering if we're the unfortunate ones to have the worst ever telephone "upgrade" or whether this is normal. I can't go into specifics here but I'm spending about 50% of my work schedule (since the beginning of December) on supporting and troubleshooting the phones.
I'm thinking the phone system needs to be upgraded again - but this time using a piece of string and a couple of empty baked bean cans (although full ones would probably still give better service right now.)