Have you inquired about your escrow?
We had a problem with out mortgage company several years ago. Actually, the problem was weeks after our mortage got transfered to another company (not by us), the new mortgage company reviewed the escrow and told us we owed a VERY large sum. I knew that was impossible. As you stated, the monthly mortgage payment jumped by about $75 a month or pay the lump sum. When I called the company, I asked them why the huge jump and they said it was taxes that went up. I highly doubted the taxes would go up by $75 a MONTH! I called the city tax dept and they verified taxes went up, but by a few dollars for the entire year. I called mortgage company back. I asked for someone else and they told me it was insurance that went up. Again, not good enough. Then they just simply said "I don't know" and was going to leave it at that! I was appauled. Then, they said it was taxes again only this time it was because they had paid the taxes for the year and we had nothing in escrow to cover it. WHAT?! Taxes had just been paid weeks ago by the previous mortgage company! It was a mess, but anyway, it got fixed. The only reason it got fixed was because I had to tell them what was wrong by doing their job!
Sorry, but I really don't know who you should complain to. I just kept asking for people higher up the food chain. Even then, it took ME being the one to tell them what was wrong!