Lots of private companies use "Medicare" in their names and websites.
These companies have nothing to do with Medicare other than possibly supplemental insurance for Medicare recipients. Be very careful with any communications you have with them. Better to go through a live insurance agent in your community, or an association or fraternal group with very clean reputations.
As to "Trumpcare," it does not exist, it is a marketing gimmick. Be very careful with private insurance plans.
And as always, do not give information over the phone to cold callers. Ask for their name, hang up, and do some research.