ST. LOUIS — Dianne Allen had been ignoring the calls from a number she didn’t recognize. But after so many, she finally relented. The woman on the other end asked if she was the owner of 8441 Midwood Avenue in Berkeley. “What’s this concerning?” Allen asked. “You could be eligible for up to $2,000 in upfront cash if you agree to use our real estate service,” the woman said. Allen needed some money to catch up on her truck payments. And before the end of that day in August, a notary was at her house, thumbing through papers for her to sign. They gave her a check for $500. “I…