The Only Way Is Essex star walked out of a scheduled appearance at fan Hannah Khan's party after being hit in the head by Haribo sweets.
Businesswoman Tina Khan, who paid £3,000 to secure Sims's appearance at her daughter's party, is now demanding a refund after the 31-year-old did not say goodbye to Hannah before she left.
Party organiser Andrea Kyriacou said that Sims had arrived late, cut short a DJ set and left early.
"Hannah was devastated and embarrassed. She's one of Chloe's biggest fans and she let her down," she added.
Sims's management told the newspaper that she was "within her rights" to leave the party when she did, but that she should have said goodbye to the girl, while lawyers disputed that Sims had failed to honour her contract.