For channels being provided on, what they claim is HbbTV, my old LG TV (a 24MT57S) receives them loud and clear in MHEG. Maybe the providers mean they are on MHEG now, and will also be on HbbTV somewhere in the future, once they've been tested.
Most of these channels say they can be accessed on t'Internet as well as telly, so perhaps people who need them could go that way. Meanwhile, I wonder if the service platform company is now searching for the plug that's come loose. If things suddenly start working, well done to the person who prodded them!