We have just had BT Infinity installed. The first attempt was a failure. I raised a fault and a different team came on Day 2.
The old master socket in the hall was re-wired, and the extension socket in my "office" was also rewired and made into the new master socket. On the engineer's leaving I asked if we still needed the line filters and was told "no" because the new master socket face plate did all that for the whole house.
After 2 days of watching the DSL light on the modem being "off" more that "on" I have replaced the filters and everything now works as it should and the DSL light is a steady green
So - don't throw your filters away - you never know when you may need them !!!