Escrow shortages happen all the time. It may be their mistake but when the payment lowered you gained by pocketing the difference when they lowered your payment. Now it’s time to pay. It sounds harsh but it’s not like the total outlay would be any different. Pay attention to taxes and if you notice the bank forgets, pay the town yourself. And refinance but only if you can get a rate 0.5 lower than your current one. The mortgage companies are all the same. I must have had 15-20 mortgages over the years. Current rate is 2.8% which I’m pretty sure will never be lower.