Samsung V+ box - channels unavailable and /or breaking up

Hi

I have a TIVO box downstairs and a Samsung V+ box upstairs.

The reception on the TIVO system is excellent, and all channels are available, so I assume that the main incoming signal to the house is OK.

However, the V+ box works for a short while after switch on, then I either get a "channel unavailable" message, or the programme starts to pixelate and break up, with eventually no signal. This happens on both the TV or an HDMI monitor. Since the cabling / filters / splitters haven't changed and it worked OK before, it sounds like I need a replacement V+ box.

Could I please book an engineer ASAP to have a look?

Thanks