I'm sorry to hear this happened to you. I had something very similar happen to me 5 years ago.... the interest rate was 4.99%, up until the day before my house closed, and it mysteriously raised to 5.3%. It wasn't the end of the world, and I still signed the document, but that sole experience is what led me to become a Real Estate Agent.

I can confirm that this type of thing happens all the time in lending. I advise all of my clients to make sure that they get at least 2 lenders working on the loan, so that if one starts playing games with you, you have a backup plan. You'd be amazed at how often that helps!

The one thing I'm not so sure about is why you are so upset with lendingtree.com. I don't deal with them at all, but I think they are just a service that these mortgage brokers use to market their services/rates. Since you aren't paying lendigntree.com money to give you investment advice, I'm not sure that it is reasonable to expect them to police all the lenders in the country.

I know what you have gone through sucks, but it happens all the time. It's part of the "bait and switch" techniques used by these lenders.

The best advice (other than getting 2 opinions) I can give is make sure you read everything before you sign. You did that and kudos to you for it.