Some people got letters saying their health insurance plans were canceled because of the ACA. That's probably just a lie. The people who sold you cheap junk insurance for profit, the people who cancel your plan when you get sick, without mental health coverage, the people who are in it for the money, are not being perfectly honest.
The ACA allows existing plans to remain in force.
Here's an article that explains how that works.
Thu Nov 07, 2013 at 11:07 AM PT: PART II—OTHER PROVISIONS
7 SEC. 1251. PRESERVATION OF RIGHT TO MAINTAIN EXIST
8 ING COVERAGE.
9 (a) NO CHANGES TO EXISTING COVERAGE.—
10 (1) IN GENERAL.—Nothing in this Act (or an
11 amendment made by this Act) shall be construed to
12 require that an individual terminate coverage under
13 a group health plan or health insurance coverage in
14 which such individual was enrolled on the date of en
15 actment of this Act.
16 (2) CONTINUATION OF COVERAGE.—With respect
17 to a group health plan or health insurance coverage
18 in which an individual was enrolled on the date of
19 enactment of this Act, this subtitle and subtitle A
20 (and the amendments made by such subtitles) shall
21 not apply to such plan or coverage, regardless of
22 whether the individual renews such coverage after
23 such date of enactment.