I sympathise, they are reaching out on a landline and leaving messages with your parents which scare them. Any sharp practices by the DWP will be done verbally, with as little record possible. Just another of the MANY unofficial ways they set out to make claiming benefits painful. Are the caller ID's blocked as they come in? If not you may be able to get a list from BT or your telecom provider of incoming calls, send a copy to the DWP and inform them you have proof of non-compliance, state that this given your explicit and recorded refusal to use the phone with them that this constitutes harassment If they are blocked then