Fans complained of seeing touts re-selling seats for hundreds of pounds, just minutes after they initially went on sale.
As a result, she has added a new date at the O2 Arena, London, on July 29.
She had already been confirmed to be in town on June 20 and June 21, as well as in Manchester on June 25 and in Birmingham on July 27.
One fan raged of the resellers: “They are selling £45 value seats for nearly £200!! so p****d off!!!! Ticketmaster is an absolute joke!!!”
“Such a shame to see @celinedion tickets for @BcardArena being sold for treble the value by ticket touts! Just spoils it for the rest of us,” another said.
Someone else begged: “@celinedion please release more dates for the UK, there are not enough and the good tickets have all gone to touts.. less dates less chance.”
The set list for the shows is by no means confirmed but fans have been speculating that it won’t be too different from what the legend has been singing at her Las Vegas residency.
That list includes the likes of Because You Loved Me, Recovering, Immortality and even Beauty And The Beast.
My Heart Will Go On, All By Myself and various covers have also been wheeled out.
Dion has sold more than 220 million albums worldwide since her debut, the French-language La voix du bon Dieu in 1981.
She released Encore un soir in 2016, reaching No1 in Canada, France and Belgium.