The stay-at-home mum was busted FaceTiming the designer whilst shopping for carpet in Carpet Court on Monday night's episode, by fellow contestant Jess.
The 'wall paper lady', as she was called on the show, could be heard giving Sara tips on styling the guest bedroom all teams have to work on this week.
Sara's conversation seems to break the number one Block rules: "No help from any outside designer."
When Jess decided to share what she overheard in Carpet Court with her 'penthouse buddies' Bianca and Carla, the girls were not impressed.
"When you're in a shop you ask for their advice, I didn't think you could phone a friend," Carla says.
"Was the C word thrown out at all? Cheating....," Bianca then asked.
Despite not supporting the phone call, the three girls concluded that after a tough week and being given last place during the bathroom judging, Sara needed the reassurance from an outsider.
In the end, Jess said if she sees it done again she would probably dob her in.
The Block continues at 7:30pm on NINE