Short notice for medical assessment.

Hi, I am wondering if anyone can give me advice. I receive PIP at the higher rate, I suffer from asthma, COPD, anxiety and depression and am unable to leave my home without support. I was sent my PIP form, days after my mother died, I requested an extension to fill it in as I was unable to cope with everything. This was granted, and a friend filled in my PIP form which included a request for a home medical. As my Dr. and CPN had not yet provided a letter, the DWP were advised that medical info. would follow.
I was sent an appointment for a medical assessment with very short notice, 2 weeks, so my friend sent a letter to ATOS cancelling the assessment and requesting a home visit. They asked for further information which was provided along with the Dr.'s letter, it was clear that ATOS only would do home visits if you were housebound. My friend sent a request that at least 28 days notice would be required for me to ensure someone was available to take me to the assessment. I was devastated to receive a letter yesterday (1/8/15) dated 30/7/15 for an appointment on 7/8/15. I don't know if I can get anyone at such short notice to accompany me. I have read somewhere that if you cancel 2 assessment appointments your claim can be disallowed. I feel like I am being persecuted by ATOS but I'm afraid to cancel the assessment again. I would really appreciate some advice.