Does BT charge to fix corroded wires??
Not if it is external to your house, any internal wiring is your responsibility.
Is your hub plugged into the master socket or an extension? If an extension, try plugging it into the test socket behind the removable faceplate of the master socket with a new filter. Also try the quiet line test from the test socket.
Instaed of keep asking questions and jumping to conclusions why don't you just answer what is asked of you?
This will enable forum members to assist you in getting you problem resolved.
To recap:
You have been asked if you are a BT Business customer. - No reply.
You have been asked to run a quiet line test on 17070 option 2. - No reply.
If you want assistance it will be given freely but you need to reply to the above before we can progress your issue.
as has been asked numerous times - are you a business user???
you appear to purposely avoid answering suggesting you are a business user and posting on wrong forum