Domino's owner threatens to 'smash' grandmother's face after she tried to return a $12 pizza

An angry Domino's Pizza owner has been captured on camera losing it at a customer who attempted to return a $12 pizza at a store in South Australia.

Mount Gambier grandmother Katherine Pickles said she tried to return the pizza on Saturday night because it looked like 'sh*t' and claimed that it appeared two separate pizzas had been smooshed together into one. 

But when she attempted to address the issue with the owner, he unleashed before allegedly throwing the pizza at her.

'Get the f***k out,' the angry pizza owner shouted in footage of the incident which has been uploaded to social media.

 'I own the f***ing store. If you don't get out, I will smash your f***ing face.'

In the video, Ms Pickles could be seen trying to calm the situation, stating: 'You don't argue with a customer, mate. You've got no idea.'

As the confrontation intensified, she called the owner 'mental' and declared: 'You're finished, mate.'

'I cried the whole way home. I didn't sleep last night at all. I'm quite shaken up by it,' Ms Pickles told 7NEWS.

'People shouldn't be afraid to make a complaint when something's not acceptable, when you've paid for it.'

A Domino's spokesperson told Daily Mail Australia that it has launched an internal investigation into the incident. 

'Domino's takes safety and wellbeing extremely seriously and has a zero-tolerance approach to aggression, harassment, or abuse of any kind in our stores,' it said in a statement.

'As soon as we were made aware of this incident, we launched an internal investigation, including into the circumstances which led to the interaction recorded. Following this investigation, we will take appropriate action.

'We have attempted to get in contact with our customer via multiple channels, including through the information provided with her order, and encourage her to reach out to us so we can discuss this important matter further.

'This customer's experience does not reflect the high standards and values we pride ourselves on, and we are sincerely sorry.'