Refused home visit for PIP

Been reading the advice on PIP people refusing home visit. Very helpful. My adult son has life-long  learning difficulties, various other disabilities and epilepsy, which is not fully controlled by medication. After having a bad fit in the centre of our village when he was on his own in September, he has been very reluctant to go out, even if accompanied with family and friends. Now he is so stressed and anxious it is difficult to get him out of his bedroom  let alone out of the house. Having medication for it may be a problem as it may well interfere with efficacy of epilepsy medication, although GP consulting with consultant. Medical consultation always by phone and shopping all done by me and husband or online. Doctor gave a letter saying he needed to have a home visit. They seem to have felt they know better. Consulted Citizens Advise Bureau after reading this site, who have suggested lines to pursue. Will also write to MP. Any other suggestions most welcome. Thanks for reading.