By Oct. 1, at least 2 million seniors will have received alarming notices: Their health plans — which they get through Medicare Advantage, the version of Medicare run by private health insurance companies — will disappear at the end of the year. Many will be stuck without a lot of options. In some cases, no other companies in their area may offer Medicare Advantage plans to replace them. This isn’t the first time this has happened. Last year, almost 3 million seniors found themselves in similar situations. An Arm and a Leg host Dan Weissmann and producer Emily Pisacreta looked into what...