Live Nation Sued Over Janet Jackson's 'Unbreakable' Tour Postponement

Janet Jackson left her fans high and dry and they're pissed about not getting concert refunds ... and one of 'em is filing a class action lawsuit to get the money.

Tiana Adams filed the suit blasting Live Nation for the fact Janet's fans haven't seen a dime ... even though she's postponed the Unbreakable World Tour at least 3 times.

In docs, Adams says Live Nation's trying to get away without issuing refunds by repeatedly treating the tour as "rescheduled" and not "cancelled." Janet's yet to pin down a date she'll get back on the road, except to say it will be sometime in 2017.

As we reported ... Janet announced back in April 2016 she was putting her tour on hold -- on doctor's orders -- to make a baby. Fans are fed up and just want their money back. We reached out to Live Nation, so far no word back.

Janet is not being sued. How could they? Look at that kid!