The soul singer's fourth studio disc Colour Me Free was expected to be released on the EMI label next month, but it has now been pushed back until the summer.
"They were supposed to be launching the album in April but now they've postponed it until July," Stone told The Mail On Sunday. "I just don't know what’s happening with it - they really need to pull their finger out.
"I've worked very hard on this record and I don't know what the plans are until EMI confirm a release date. There's a world tour planned and everything is in their hands. I really don't know what is going on."
Stone recently embarked on a tour of smaller venues, which allowed the star to "test out" her new material.