Hefner told Harris to keep her engagement ring, a Bentley car and their dog Charlie following the couple's June split. Harris later attempted to give the pooch back to the 85-year-old Playboy founder and editor-in-chief and he refused, but Hefner has recently changed his mind and wants the dog back.
However, Harris is no longer willing to give up custody of the couple's Cavalier King Charles spaniel, and Hefner's ex-girlfriends Madison and Wilkinson -- who, like Harris, were former Playmates -- are furious that Harris isn't cooperating.
"Why did you voluntarily give the dog to Hef (who loves him too) after you left, only to ask for him back a few months later?" Madison, who stars in Holly's World and also appeared on the eighth season of Dancing with the Stars, wrote on her Twitter account Monday.
"Dogs shouldn't be yanked from happy homes on a whim. She needs to quit attention-seeking!"
Wilkinson -- the Kendra star, who also competed on Dancing with the Stars' twelfth season -- subsequently tweeted her support to Hefner on Tuesday, saying she was "sorry" he had to "go through this."
"That dog loves you so much. She abandoned him and now she wants him back. She's mean, mean mean," Wilkinson added.
Hefner told People last week that Charlie is worth more than a dollar value to him, and he hoped to work the situation out with his 25-year-old ex-fiancee so he could get him back.
Hefner and Harris got engaged over the holidays last December but Harris called off her wedding this past summer just days before she was set to walk down the aisle.