The Celebrity Big Brother housemate parted company with Powell's Can Associates in June. It was rumoured at the time that the 30-year-old had been dropped due to her partying.
Since the split, Powell has claimed that Katona was "very demanding" of her.
"She constantly needed attention and there were a lot of things to put straight at the beginning, so it was quite difficult," the PR guru was quoted as saying. "It's true that she owes me a lot of money, but she's going to work that out."
Katona hit back in her OK magazine column: "I was a little bit peeved that Claire Powell went public and what she said about our break-up. I've always been professional during my time at Can Associates and always worked really hard.
"We both know the real reason I left and what made me unhappy with the management of my career."
She continued: "I will sort out any problems that have arisen in private with the help of my new management team. I know what caused the mess but I just want to move on and put the past behind me."
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