You can do this with a Logitech Harmony universal remote such as the Elite or any of the other versions that come with the Harmony Hub. This will allow all the equipment to be controlled through Alexa and is reasonably intelligent, in that once it's all set up it will keep track of which devices are on etc. so for instance if you say "Alexa, turn on virgin" it will turn on the TV, switch it to the right channel and switch on the Virgin box, if you were then to say "Turn on DVD" it would change the channel on the TV, turn off the virgin box and turn on the DVD player etc. Obviously though, this does mean an additional purchase and some time spent getting it all set up.