"It just went black, then it logged me out. I tried to log back in and it said an error had occurred ... and then I just had this feeling that there's no turning back."
Koumakis had just listed a dress that she'd described in the caption as being "replica Chanel". She suspects she was caught out by Instagram's automated systems, which picked up those keywords and thought she was selling a knock-off.
She lost all her clients and had to start a new account from scratch.
"It just felt like everything was sucked out of me, because [the account] was how I was earning money," she said.
Instagram has become increasingly popular for selling items like clothing, homewares and art through business profile accounts.
The app has special features for these accounts to make running their business easier, as social media marketer Tanydd Jacquet said.
"Instagram markets itself as an effective and affordable tool for small businesses, so it's got a lot of potential for people who are trying out market validity for their product or a way to experiment with a small business."
Hollie Schwass also lost her Instagram store, being told she had breached community guidelines - but she doesn't know which guideline she breached because Instagram hasn't been in touch.
She instead opted to make a new Instagram for her store. Rebuilding it from scratch was not easy, and attracting followers took time.
"If you're restarting with, you know, 10-15 followers you're probably not going to make many sales for a long time," Schwass said.
Schwass has since had her account reinstated, and was using her rebuilt account as a backup in case it happened again.
Koumakis said the help centre did not provide enough information relative to the circumstances, and there was no one to directly talk to.
"There's no customer service helpline. It's just such a big business that they can't have humans working directly with people," she said.
A spokesperson for Instagram parent company Facebook said they reviewed content and accounts with both their automated systems and humans, and that tens of thousands of people were employed to investigate.
"Instances when accounts may have violated our community standards can be nuanced, and that's why we have - and will always have - a need for people to look at those reports and make decisions."