Yeah, I just asked for a better deal. I did call straight through to retentions but I didn't threat or even suggest that I wanted to leave.
I actually started on 50Mb, I rang them up asking to be upgraded to 100Mb early, and to see if I could get a discount, and I got both. They even upgraded me to 100Mb while I was on the phone mid call, and by the time the call had finished my modem was syncing at closer to 110Mb than 100.
Roll on 120Mb!
Edit: Oh yeah, when I signed up it was a 2 year contract, but for some reason they also dropped it down to 12 months, weird (they actually told me this on the phone).