The girl group launched a London stage show, Viva Forever!, based around the band's hit pop songs, in December but theatre bosses decided to close the production eight months early due to slow ticket sales, reported Daily Star.
The curtain will come down on the show for the final time on June 29 and Bunton insists critics did not give the musical a proper chance.
"For all of us it was heartbreaking. Okay, at the start the cast needed to get used to it and they needed a few things changing, but now it is just brilliant. We couldn't get past people being a bit negative and that is a shame.
The musical was hit with a slew of negative reviews from theatre critics, who branded it "insultingly banal" and "tawdry, lazy and unedifying".
