If they say that they're working on it, they're working on it. There is no way to speed things up - as, as I said, the source of the irradiation/distortion has to be found and fixed.
And please understand that cable networks work completely different than telephony lines.
Whereas you have a dedicated line for telephony lines / DSL lines and thus a distortion is mostly only affecting your line (or in rare occasions some lines in your house as they are all going out of the house as a single bunch of lines) and thus it can be fixed very fast, cable internet works completely different.
Cable networks use a shared structure meaning that multiple houses are connected to a single main line -and yes, this main line is only one cable- and thus an irradiation/distortion coming from any of the houses distords all(!) connections to all(!) of the lines connected to this single main line. And this makes finding an error so much more complex and time intense than it is with DSL/telephony lines - as you have to check in each connected house if the source of the irradiation/distortion is placed there. And it's even more complicated if the owners won't let you in and/or the irradiation source is not distorting the signal all the time but only to certain times [like a device that is not connected to the cable network all the time -or- a device placed next to cable network equipment that irradiates heavily, as some "cheap" power supply units (mostly from china).
