Refinance cause cannot sell

Mortgage companies are telling me that if a property has been listed for sale within 6 months, one cannot refinance (house did not sell; want to lower payments). Why is that?

That's not necessarily true. Depends on the mortgage company because underwriters, who approve or disapprove the loan, usually don't like to see that the home's been listed on the market. However, I have done deals where the home was on the market for 120 days.