Mortgage: Trouble during payment process

In XXXX we received notice from XXXX XXXX that are property taxes were delinquent and home would be put up for sale XX/XX/XXXX. We have consistently paid more than required monthly mortgage payment. Our loan was sold to New Rez LLC prior to first payment but the required monthly payments were the same as our initial paperwork with our bank. I contacted New Rez and sent documentation regarding property taxes. They had only been making payments to escrow to cover home insurance and the approximately $ XXXX tax on vacant lot adjacent to mortgaged lot with home but not on the home lot. ( Taxes are approximately $ XXXX ). New Rez did make payment on delinquent taxes which has now put my escrow account in a huge deficit. I have contacted customer service regarding this numerous times as there is no way my escrow account ( now negative $ XXXX ) will ever have enough funds to make the XXXX property tax payment. Also they are not showing correct taxes due for next year. They simple entered what they paid for delinquent taxes in XXXX as what is due in XXXX. I contacted them regarding this and requested a new analysis over a month ago. Nothing has changed. I spoke with customer service regarding the deficient escrow account and was told I could make a XXXX time payment with Escrow payment noted on check. On XX/XX/XXXX my bank sent a check for {$2000.00} with " escrow payment '' annotated on check. New Rez applied it to my monthly payments- my escrow account remains negative $ XXXX. I have contacted them numerous times- lots of talk no action. I am sick to think I have a XXXX yr loan with them which was out of my control. I would gladly refinance with another company if/when the interest rate is comparable.