It is not a deceptive practice; there is no guaranty of when you will get a loan, or even of getting it at all--those preapprovals you get in the mail are NOT gurantees of a loan, since no loan is guaranteed until after it goes through underwriting and the bank/lender actually guarantees it. While you may not have understood that, it was not deceptive; it's simply the case that no loan is ever guaranteed until you in fact have it, and lenders may take time to process it, or even decide to not loan to someone who received a mail preapproval.Further, if you were not able to get the loan becuse you started putting things on credit, altering your debt-to-income ratio, that is not anything the lender is responsible for: it is something you voluntarily did. You did not have to borrow money while seeking loan approval (and in fact, it is strongly recommended that you don't).Basically, you received nothing more in the mail than offer to apply for a loan, which you did. Nothing was committed to or guaranteed, and there was no deception, at least from a legal point of view.