Can an assessment be split in two?

I was told I should hear within a week and if not to phone them next Friday (which is the 10th, therefore ten days before the appointment.) I don't understand why, having agreed a home assessment for the first appointment, they don't want to agree one for the second. There is no way I can travel all that way, have a two hour assessment and then travel back again.
But rest assured, I won't leave things to the last minute. This is turning into something of a nightmare. I am writing up details of all the phone calls in case I need them later.
Thanks as always for your advice.

Another update.
Phoned up today and asked what was happening. The long and the short of it is that Capita are still insisting that I attend a two hour assessment at an assessment centre. This is on top of the bungled one hour assessment that was done at the end of July and never finished. This will be on August 20th but I still haven't had an appointment letter and initially at least, nobody could tell me the time of the appointment.

Apparently - because eventually I got through to Customer Relations, - my form for the review was no 'robust' enough for a paper assessment (although the initial assessor said it was), and they had spoke to the initial assessor (the one who took an hour to go through my meds and didn't even ring the bell) and between them decided that my case was 'too complex' for a home visit.

Customer Relations said they would ask again for a home visit for me, but (as Gordon has already said) if that isn't granted then I will have to attend.
I have had a letter acknowledging my complaint about the first visit. I have not received a letter for the appointment. I have asked them to please make sure they send it to me. (And I did eventually find out the time from Customer Relations.)

Nobody seems to understand that if I was disabled enough to warrant a one hour home visit at the end of July I am surely disabled enough to warrange a home visit in August. I honestly don't know how I am going to manage this. It's worrying me sick.

Thanks Gordon, I'll definitely do that. Many thanks. I'll let you know how I get on.