When I try and watch a recording now I get part way through and it starts buffering , starting and stopping and loses the sound. I have checked aerial signal strength and all is fine, and it doesn’t buffer at all when just watching tv , is the box faulty ? If so who do I contact to obtain a replacement?
When you say the aerial strength is fine exactly what figure is shown?
Quality is the really important number & should be 100% and strength should be in the 80-90% range typically, anything higher can overload the tuners.
It sounds like the hard disc in your box may be on its way out 😢
But it may not be that bad, so the first thing to try is a reboot. If this is ineffective, then try a Reset, Keep Recordings. Both are described here:-
https://www.bt.com/help/tv/fix-a-problem/tv-boxes/how-do-i-reset-my-bt-tv-box-#:~:text=Select%20a%20....
Depending on if this is/was a recording issue, or just a playback issue, existing recordings may remain affected, so you may need to try new recordings made after the reboot or reset to see if it has been effective or not.