On Monday, Montag, 23, began shooting a cameo in the comedy Just Go With It, starring Adam Sandler, Jennifer Aniston and Nicole Kidman. When reached for comment, Montag's rep told Us Thursday: "Aiden had nothing to do with securing Heidi's role in the movie."
But a source tells Us that Montag was "horrified" when he showed up on set, "demanding a significant portion of her Hills money."
The source adds that when Chase, 40, recently followed her as she filmed MTV's The Hills, he tried to "move onto Audrina [Patridge]," whom he not only offered his healing/spiritual services but also asked to be her manager, the insider tells Us.