This is a bit of a novel of a post, but wanted to include everything I know in the hope someone knows something about this, because I sure don't.

My inlaws live in Wainuiomata, Wellington. They have a cable TV service provided by Vodafone. For some time now they have been having trouble with it. They called Vodafone, who sent someone out, but the problem persists, and the tech eventually blamed their TV. I went over and had a look today. I couldn't get it working, but I don't think it's the TV (I'm happy to be proven wrong though, if it can solve the problem).

It's hard getting anything from the inlaws as he is pretty much deaf so can't hear anything I say properly, and is Dutch and doesn't speak very good English, and doesn't know much about technology. She is not very bright, and is even more technologically challenged - she struggles to use anything more complicated than a toaster.

• I believe their original TV/phone package was supplied by Saturn, and when that ceased to be a thing I think it went to TelstraClear, and then to Vodafone.
• There's a concrete power/telephone pole outside the house that has some large grey plastic sleeve running up it with Saturn written on it. This sleeve is not attached very well and the cable that should be running in it from the ground to the top of the pole is hanging out towards the top.
• There's an overhead cable running from the top of the pole to the gable on the nearest corner of the house. This cable then runs along inside the guttering to a downpipe. It runs down the outside of the downpipe, attached with cable ties, and into the bottom of a grey plastic box with Saturn printed on the outide.
• Inside the garage there's an RF/coax/antenna looking cable that comes through the wall from the back of the grey box, runs along/up the wall, through the floor, into the living room behind the TV. Here things get a little untidy.
• The RF cable goes into a two-way splitter. One of the two RF cables on the output side of the splitter goes into an old Motorola Surfboard modem, and the other RF output cable goes directly into the back of the Vodefone TV decoder.
• Also coming out of the modem is an RJ45 plug-looking ethernet cable that is connected to the back of the decoder, similar to my Sky decoder which I think allows remote booking/recording of programmes.
• The decoder is not the little Apple TV-looking box that I see on Vodefone NZ's website now. It's a bigger black box, about the size of my MySky decoder, with nothing on the front but a light in the middle that shows red (off) or blue (on) and a round set of menu/arrow/enter buttons on the left - no other buttons/words, etc. I could see. 
• The decoder is connected to the TV by HDMI cable. Also connected to to the TV is a bluray player (HDMI) and a VCR (RCA) - neither of which I think they actually use, but don't want to get rid of. 

Several days ago, it stopped working. The only image on screen is a static picture that looks like two circles/spheres. The one on the left has some lines/shapes on the surface and the one on the right looks clear, but with a shadow/silhouette that looks like someone holding a sword. You can hear the audio of whatever channel they select, but it keeps cutting out (e.g. plays for about 30 seconds then stops for about 10 seconds) but all you see on the screen is the still picture of the two big balls.

They called Vodafone, who asked them to do a lot of stuff, but with him being deaf and not good with English, her not knowing which button on the remote is "On", and the customer service rep probably being in the Philippines, that didn't help. Vodafone sent a technician, he fussed about, told them the decoder was overheating because it had something on top of it, so gave them a new decoder and stood it up on its side next to the cabinet the TV sits on.

They tell me it worked "for a while" (a few hours?) with the new decoder, but do seem a bit confused about that. But it went back to the same problem, and the tech is blaming the TV, saying there is a problem with it.

I rebooted the modem, restarted the decoder, tried switching the HDMI cables between the decoder and the bluray player, and the TV inputs the HDMI cables were plugged into. Whichever combination of HDMI cable and TV input I use, the bluray player works perfectly but the decoder displays the same static image.

They also say they saw a Downers tech up a ladder working on a power/phone pole across the street a few days ago. They didn't see anyone working up their pole "but we had been out earlier." I'm going to try phoning Vodafone tomorrow, but as I'm not the account holder, and won't be at their house when I call, I'm not sure I'm going to be able to resolve much.

Does any of this mean anything to anyone? I wonder if there's a problem with the signal they're getting from the cable? Could there be a loose or faulty connection, or something disturbed by a Downers guy up a pole? But where does the static image come from? And why is there sound (though cutting out) and no video?