I worked in a dealership for 7 1/2 years (not Ford) and unless the customer is a known trade customer, nothing gets ordered in without payment in advance, my local Ford dealership is the same, but while at my old place we would take payment over the phone, at Ford they don't so to special order something I need to go in and pay up front, then go a couple of days later to collect, a slight inconvienience but I completely understand why.
Too many customers call up and order things they will never come in for, dealer parts departments have stock targets and unsold special order parts (which manufacturers won't take back) means a lot of ass-kicking, then the parts hang around so long they go into "obsolete stock" and start costing money.
In the case here although the OP has diagnosed the fault a garage never usually takes their word and wants to diagnose for themselves, battery voltage when the engine is running could also be a wiring or charging relay fault, then the dealer is left with an expensive part to sell.
I completely see the stress and inconvenience, it's just bad luck the alternator failed when it did, it's not the dealers fault that it failed. I do think their downfall is not offering a courtesy car though, but these things are usually booked weeks in advance and not always available next day as you needed.
Just one of life's hurdles I'm afraid.
At least you saved money by fitting it yourself!