Thankfully, she was found by the St John Ambulance crew who helped her until her husband arrived.
She then proceeded to have a panic attack that lasted for two hours, leaving the terrified woman convinced she was going to die.
"I was so sure I was going to die I asked Adam to say goodbye to my girls and tell them how much I love them," she said.
"I remember asking, 'Why would someone do this to me? Who would want to hurt me?'"
All it took was around 15 minutes from her first sip of wine for Ms Marmion lose all motor skills, be unable to move her body or respond to anyone.
She said she followed all the normal safety precautions people were taught to avoid something like this happening, such as not leaving your drink unattended and being in a "nice and well-lit" establishment.
Ms Marmion ended the video by stating it was one of the most terrifying experiences she had had and warned others to be careful.
She wrote on the post that she was reporting the incident to the police and heading back to the bar to see if security footage can help determine what happened.
Her video has been viewed over 83,000 times and shared by nearly 3000 people.
Social media users were quick to sympathise with Ms Marmion and share their outrage at the shocking attack.
"Hope you're ok now Mandy. Something that you think only happens in the seedier bars but obviously not anymore," one social media user wrote.
Another said: "I'm so sorry Mandy. What a terrifying experience. Some people are so wicked."
Other users claimed they had had similar experiences happen around the Salamanca Place area, with some saying it even happened on the same night as her.