How stressful. Without knowing all the details I think they're being a little unfair to you. Will they discount the cost of the day if he can't be there past 2pm?
I'm sure you've considered this, but are there other care options for you? FDC or a nanny, even if the care is shared between the centre and the nanny (ie they could pick up your DS and look after him for a couple of hours in the afternoon). It's tough when money is an issue, hopefully your DHs business is successful and you can scale back your work hours if that's what you want to do.
Big hugs to your DS, it must be difficult for him too.