Seven Year Switch's Cassie received a letter that would infuriate the calmest of parents.

Seven Year Switch star and mum-of-three Cass Thistleton has just experienced one of those life moments we all live in serious fear of, receiving an anonymous passive aggressive note in her letterbox.

“This letter was left in my letter box today!” Thistleton wrote in an Instagram caption accompanying a snap of the letter. “Funnily enough my children haven’t been home for 5 nights!”

The letter begins, “I am writing to you to complain about the really loud noise your children make. This is a quiet neighbourhood and you and your kids make it the opposite. The constant screaming from your kids is ridiculous. Everyone in the neighbourhood hears every noise you make when you are outside.”

A post shared by CASS THISTLETON (@cass_thistleton) on Jul 18, 2017 at 6:36am PDT

“I have told the people who own your house and so have other neighbours cause they live next to you. But they must be as bad as you cause they haven’t told you to be quiet. Show some respect for the people that live here. Some of us are shift workers and don’t need to hear your kids screaming and yelling. If you won’t stop the noise we will all send letters to the real estate and complain,” the typed note continues.

Understandably, Thistleton wasn’t having a bar of it, pointing out that her daughters are never outside before 9am and always inside before 5pm.

Listen: Holly Wainwright discuss the highs and lows of parenting on This Glorious Mess. Post continues… 

Interested in resolving the issue – despite the fact that her children have been away for an entire week and unable to make noise – Thistleton says she approached her neighbours on Tuesday, hoping to “give them the opportunity to have an adult conversation and to let them know that I am the most approachable, accomodating [sic] and considerate person who would no doubt respond well to a quiet chat!”

But, sadly, the anonymous author has decided to stay just that.

“Surprise surprise the culprit is still unknown and no one owned up to the letter!” Thistleton says.

“Seriously, what is this world coming to?” she asked finally.

Thistleton and her three daughters moved into the rented townhouse earlier this year after she and her long-term partner Ryan announced they were separating. The decision came almost one year on from the two taking part in the premiere season of Channel 7's relationship reality show, Seven Year Switch. 

"We’ve got beautiful children together and they’ve been the glue that’s been keeping us together for this long," Cass said at the time, adding, "Staying together for your children is not the right reason, you need to be happy."

In March, Thistleton told Mamamia that Ryan is still living nearby and is at their house "all the time" to spend time with the children.