Dude, where's my car?

Ok, we're now a MONTH overdue on the delivery of my car and still no sign of progress. I had to ring motability again today and get another extension until the end of the month. I asked the (very nice) guy if he could tell me what the hell is going on and I finally got a coherent response....

Since I ordered this car, the model spec. has changed (for the better I hope!) and so they cannot release the cars until they work out how much I have to pay a month. I was already going to lose the total amount of mobility component from my Disability Living Allowance so if that change means I get some money back I shall be rather pleased. However...

I just checked the Motability website and the only Fusion Zetec they have has a £350 deposit. Y'all better hide in the basement cos if they try making me pay an extra £250 there's gonna be a fucking nuclear explosion.