https://www.gpo.gov/fdsys/pkg/PLAW-111publ148/pdf/PLAW-111publ148.pdf
PART II—OTHER PROVISIONS
SEC. 1251. PRESERVATION OF RIGHT TO MAINTAIN EXISTING COVERAGE.
(a) NO CHANGES TO EXISTING COVERAGE.—
(1) IN GENERAL.—Nothing in this Act (or an amendment
made by this Act) shall be construed to require that an individual
terminate coverage under a group health plan or health
insurance coverage in which such individual was enrolled on
the date of enactment of this Act.
(2) CONTINUATION OF COVERAGE.—With respect to a group
health plan or health insurance coverage in which an individual
was enrolled on the date of enactment of this Act, this subtitle
and subtitle A (and the amendments made by such subtitles)
shall not apply to such plan or coverage, regardless of whether
the individual renews such coverage after such date of enactment.
(b) ALLOWANCE FOR FAMILY MEMBERS TO JOIN CURRENT COVERAGE.—
With respect to a group health plan or health insurance
coverage in which an individual was enrolled on the date of enactment
of this Act and which is renewed after such date, family
members of such individual shall be permitted to enroll in such
plan or coverage if such enrollment is permitted under the terms
of the plan in effect as of such date of enactment.
(c) ALLOWANCE FOR NEW EMPLOYEES TO JOIN CURRENT PLAN.—
A group health plan that provides coverage on the date of enactment
of this Act may provide for the enrolling of new employees (and
their families) in such plan, and this subtitle and subtitle A (and
the amendments made by such subtitles) shall not apply with
respect to such plan and such new employees (and their families).
http://obamacarefacts.com/grandfathered-plans/
The text is directly from the law. If your insurance company told you they had to change their existing plans they lied to you and screwed you over.