This is separate to any issue I've had with Virgin Media, but if I do go with their ADSL product, it requires a working phone line, which I'm not sure we have at the moment.
When our phone line was installed, it was done about 19 years ago by a friend who was a qualified BT engineer. At the time, the phone was in the kitchen, so that's where the master socket is. The line from the telegraph pole comes in the front wall, attached to a silver "bell" housing, there's a flat wire running for about 6 or 7 metres down the front door frame, under the carpet, and into the master socket. Since the phone is now located in the living room about 2 metres from the "bell" housing, and is currently on about 10m of extension cable since there's nothing custom for the distance from master socket to phone area, I'm wondering whether that could have any bearing on the broadband connection randomly dropping out. When it does, I do 17070 and option 1 for a BT quiet line test, and there's a faint fuzzing sound, but it happens so randomly, the chances of a BT engineer actually picking up said fault is probably close to 1000 to 1! The modem complains about not picking up a dial tone, we're constantly changing the ADSL filters, and they get swapped every couple weeks. Thoughts? (I'd like it to be the million-to-one chance, but that's just not gonna happen. At all!)
It could also be the modem (Speedtouch 330).

Don't tell me to replace it just yet, I have a spare at the ready to plug into it.
It could also, I thought, be something to do with BT having enabled 21CN WBC in our exchange (Lowestoft). The modem's about 5 or 6 years old, when did BT start shifting over to the "new" PSTN network? Could that have any effect on the modem dropping a connection and the cracks and hisses the phone picks up?
Or is it likely the installation just needs a complete refresh to bring it up to our new needs and modern standards?
How much is that likely to cost if BT actually do find a fault with the line?