seterus seterus is holding my money in an escrow account and won't apply my payment to my mortgage Nationwide

My mortgage payment has gone up $175 dollars per month.  I have my payments going out through automatic bill pay with my bank.  BEFORE the payment was due, I called Seterus and notified them that the old payment was sent and I was sending the additional payment to reflect the total of the new balance due.  They assured me they would take care of it and that it wouldn't be a problem.  What did they do?  They applied both payments to the escrow account because "the payments were separately insufficient."  Now, I'm getting a bill stating I'm delinquent!  I have called them 3 times  to rectify the situation.  They were NO HELP and did not rectify the situation (I even talked to a "supervisor")!  They assured me that if it goes to the credit bureau, they would take care of it.  They can't even take care of their own billing, how am I to trust they'll take of the credit bureau.  It shouldn't even go that far!  It seems like this is some sort of tactic to illegally hold my money in an escrow account and not applying my payments to the principal as it should be.