The issue of interference to short wave from power line networking devices was debated in Parliament yesterday. You can view the televised debate here. It's quite long, but worth watching if you can spare the time.
If you don't, here's a summary: The only complaints are from a few hobby radio amateurs and the number of complaints has been too few to justify banning a technology that brings potential benefits to millions of homes.
Other points: "Hobby radio amateurs are not legally entitled to a completely clean radio spectrum", and "no specific limits on interference levels have been set so that radio users can adapt as the use of PLT technology evolves." It is also projected that the number of installed PLT devices will quadruple by the year 2020. So this spectrum-destroying interference will be coming soon to an antenna near you!
I'm afraid that the writing is on the wall for amateur radio. In today's world, the only things that count are money and big business vested interests. There are too few radio hobbyists to count at the ballot box and they don't contribute anything to the country that can be measured in financial terms. So we are just going to have to "adapt" to increasing interference levels by giving up hope of receiving weak signals, confining our activities to quiet portable locations, or using modes like D-Star which are interference-free once the signal level rises above the noise threshold.
I think we just saw a death sentence passed on our hobby!