I reported the same issue of losing Chanel Bonding in Sept and it still hasn't been resolved. I am getting no benefit from a DOCSIS 3.0 modem at this point. I also of coarse get slow speed during any peak hours without the bonding to help out. My signal levels and SNR are great, so has to be a head-end issue.
I PM'd Chad but of coarse nothing was wrong that he could see and only could setup a Tech Visit. A home tech visit will do nothing as it is either a policy change to not bond certain service levels, some joker at the head-end who has messed with the settings or an equipment failure or they moved equipment to another area (this has happened in the past when a larger area had a failure and they took our local QAM up-steam card and replaced it with a QPSK (slower) model.)
Here is my thread: »[Cable HSI] Channel Bonding