You should get in touch with your conveyancing solicitor as this was an "undisclosed dispute" which should have been resolved before you took possession of the property.
Write and send by recorded delivery a letter to Craphone Whorehouse telling them that the Talk Talk service that is on the line is nothing to do with you and should be removed with effect from the date that you took possession of the property. Charge them line rental until this is performed.
Finally, speak to the Office of Fair Trading and youl local Citizens Advice Bureau as they may also have advice that can resolve this.
SHARK!