As singer-songwriter Beck, 44, accepted his Album of the Year Award for "Morning Phase" at Sunday night's 2015 Grammy Awards, Kanye West walked on stage to interrupt him but changed his mind and returned to his seat in the audience.

Initially, everyone thought West's stunt was poking fun at his infamous 2009 MTV VMAs interruption of Taylor Swift's award acceptance speech, but at a post-Grammys interview, he made it known that it wasn't a prank. He felt Beyoncé should have won the award for her self-titled album.

While some view West's inappropriate behavior with amusement, Garbage lead singer Shirley Manson is furious. Manson, 48, wrote a message to West, 37, on her Facebook page addressing not only his diss of Beck at the 57th Annual Grammy Awards ceremony, but also comments he made at a Grammys post-show.

Regarding West's attack on Beck's worthiness to receive the award, Manson said, "You make yourself look small and petty and spoilt ... Grow up and stop throwing your toys around."

West told Access Hollywood at E's Grammys post-show, "When you keep on diminishing art and not respecting the craft and smacking people in the face after they deliver monumental feats of music, you're disrespectful to inspiration and we, as musicians, have to inspire people who go to work every day and they listen to that Beyoncé album and they feel like it takes them to another place."

"Dear Kanye West, It is YOU who is so busy disrespecting artistry," Manson's message reads. "In attempting to reduce the importance of one great talent over another, you make a mockery of all musicians and music from every genre, including your own."

She added, "Ps.I am pretty certain Beyoncé doesn't need you fighting any battles on her account. Seems like she's got everything covered perfectly well on her own."

Manson is a Scottish singer, songwriter, musician and actress, best known as the lead singer of the alternative rock band Garbage. For much of her career she traveled between her home city of Edinburgh, Scotland and the U.S., but she now lives and works in Los Angeles.