Negotiating a Lease due to change of terms by the Deal

I am going to lease a Cayenne and plan to pick it up this week. I built the car
and put some amount down for the same. We had initially signed-up for a 39
month lease but this week the dealership told me that they could only approve
me for a 18-month lease because my visa expires around that time.. That felt
unexpected because this was never discussed and I do have a valid document
(I-140) that can extend my visa but the dealership is saying that the bank is not
going to accept this? They are now offering me an 18-month lease which is
~250$/mo more expensive than my previous deal. Any idea how I can
negotiate with them to keep the original terms of the lease?

Happy to help with details of the lease also if needed.