Reported mains hum on the line the problem is when it was installed over 20 years ago when virgin media was nynex it was spliced into the BT Bell and extension to get the phone upstairs working. The customer service rep heard the noise on the lime and promised to phone back never did wish to now raise this issue to the next level. Really annoyed with customer service as not listening to customer.
Thanks for clarifying this! It sounds like you may need an engineer appointment - I'd be more than happy to get this sorted for you, I'll just need to confirm a few details via Private Message. Please look out for a purple envelope in the top right corner of your screen.