He has been given incorrect advice by his local Jobcentre Plus (JCP) office. Although JCP prefer it if a claim is made by 'phoning a contact centre, a request for a clerical claim can not be refused., there are situations such as folk wi hearing or language difficulties being unable to make the claim over the 'phone.
He, or someone on his behalf should contact the local JCP and ask to speak to a First Contact Officer and explain the situation. A face to face interview can be arranged which will speed up the process rather than waiting for a clerical claim to be sent out, completed and returned.
Whether the claim is made by clerical claim or face to face, you must make sure that a request for backdating is made and detail the previous requests made for a claim as that will ensure any benefit awarded is paid from the earlier date.
If they still insist on a claim being made through the Contact Centre, ask to speak to the Manager.