pip - visiting officer

A family member is in the process of being transferred from DLA to PIP. He never got around to replying to letters informing him of the change. Out of the blue he had a call from a mobile no. saying they wanted to check that he had received the correspondence. The lady at the DWP also gave a phone no. to ask for a PIP claim form. A few days later a PIP1 claim form arrived in the post even though he had not rung the claim line. We subsequently rang to ask for an extension of time so that he could go to the CAB as he needs help because of mental health problems. The lady said that the family member was logged to receive a visit from a Visiting Officer. They did mention the "How your disability affects you form", so it may be PIP2 form not PIP1. The family member needs the help of the CAB and would be extremely distressed to receive a visit from a visiting officer. Does he have a right to insist that only the CAB assists him to complete all his PIIP forms rather than being distressed by an interrogation from a visiting officer?