Hi @Lacey101 welcome to the community and thanks for posting, I'm sorry to see you're having problems with your BT TV service. What model of power line adaptors are you using to link your hub to the Youview box? It could be the adaptors or your broadband connection, what broadband speed are you getting at the moment?
Some powerline adapters can upset your broadband speed, so it may be worth checking your download speed with them disconnected
TP Link ones seem to be a major source of problems. See the following threads on the forum.
BT Infinity VDSL worse performance than ADSL
However there is a fix for the TP Link ones which was posted by davejanney, one of our forum members. Thank you.
You need to download this utility TP Link utility
Once you have it open go to the ADVANCED settings for the adaptor that is connected to the router. on the left hand side of the menu is MODE.
Within the mode settings there is an option to LOWER PLC-TO-VDSL INTERFERANCE MODE.
Now it warned me i would see a drop in speed however the change was instant! the speed on Speedtest.net doubled when running through the adaptors, and it is rock solid stable. i downloaded a 1Gb file with any connection drops, before it would have dropped out every 30sec.
See this post on the Plusnet forum Powerline Ethernet - A warning