They should but some can be awkward as it’s not really ment to happen but no one says they can’t do it either. My Peugeot dealer changed mine without me even asking and it was for nearly 2k. I asked a Hyundai dealer would he do it and he said no problem.
I can see a few big changes coming to motability soon and one will probably be the ap you agree to at time of ordering will be what you pay regardless of up price going up or down.