Cab medallion owners in Chicago say banks should be doing more to help them climb out of financial troubles they say were brought about by ride-sharing companies like Uber and Lyft. Dozens are raising the concern with LOMTO Credit Union, a New York-based lender that has financed medallions in Chicago. They said LOMTO has been unwilling to modify their underwater loans — but the bank has faced its own financial troubles since federal regulators took control of it last month.