Mel B and Mel C are reportedly struggling to agree on details for the upcoming Spice Girls musical.

The production has been in the works since early 2010 and will feature the British girl band's biggest hits. Theatre producer Judy Craymer is working on it, having previously lent her services to Mamma Mia! The script is being penned by comedienne Jennifer Saunders, but is apparently taking longer than was first thought.

Victoria Beckham, Emma Bunton, Geri Halliwell, Mel B and Mel C are supposed to be heavily involved in the musical. However, the two Mels apparently are not seeing eye to eye.

"Melanie Brown [Scary Spice] and Melanie Chisholm [Sporty Spice] can't agree on anything," a source told New York Post.

"It's driving Jennifer crazy."

Also problematic is Victoria's hectic work schedule. The star lives in Los Angeles, where she raises four children with David Beckham. She also has a successful fashion label and is constantly busy working on various collections for it.

This made it difficult to pin her down.

"The show, which has been scheduled to debut in London by year's end, has reportedly been delayed before because of the busy former pop stars' scheduling issues," the publication reports.

Although the musical will feature the famed band's songs, it won't be about them. Instead it will follow a mother and daughter as they go to a talent show.

Mel B has been spending a lot of time in Australia recently, thanks to her role as a judge on the country's version of The X Factor. She is also set to host Dancing with the Stars there and has now decided she wants to permanently set up home in the sunny country.

"I would love to become an Australian citizen," she told Australian newspaper Daily Telegraph. "I've set up shop here. We are all really happy and settled."