I'm the mum of a new student and we sat down at 7pm last night to "choose" a room and they were pretty much all gone. I cannot tell if we did it right or wrong but all his preference places weren't visible and I assume they had been released in batches and we needed to log in at 4pm on the dot. It seems like a horrible process, and it was completely pointless filling in preferences a few months ago - the idea of picking your room by other flatmates was just laughable, the whole thing was really stressful.
In the end we booked in Maple Bank - and were forced to go with student living plus - there was no self catering available. Even with SLP this accommodation is cheaper than the other stuff in the Vale (or the other Selly Oak rooms which were still there), so we have just taken the hit to get the room in the right location. It seems that they have the same facilities in all flats so I cannot understand why some are forced to be catered. It seems clear that you cannot unsubscribe from it, although I would be interested to know if you manage to do that. We've been going back and forth about getting in touch and seeing if it can be changed, but he now seems happy to buy sandwiches every day and I feel we are fighting to pay thousands more and have him total self cater all for the sake of an en suite bathroom. I'm sure we read that you could cancel within 7 days of the booking, but of course this would be enormously risky if you want accommodation, so your best bet is to call their accommodation office and see what they can do.
If you are in Maple Bank do check out how the prices compare as you may find you are still paying less than other Vale accommodation and then you would have to buy your own food all the time anyway.
I'd really appreciate it if you can let us know how you get on if you do give them a call.