Lending Tree Pree approved letter with pre approval code unknown Nationwide

Have received several pre approved loan offers from Lending tree with a pre approval code. When I would go to the web site to input code the code was not accepted with message that the code does not exist. I called the customer service number and was tol to go to Lending Tree .com and input information. I input information and sent only to receive a denial on the pre approved loan as soon as I hit enter to send. This company needs to be stopped sending these bait and switch letters just to get your information to sell resulting in more emails,phone calls and mailings.