A nail salon customer has been praised for calling out another customer's rude behaviour after her appointment ran 15 minutes late.

Karina shared a video on Saturday of herself as she interrupted a woman who was being 'disrespectful and verbally abusive' towards the owner of her favourite nail salon in Adelaide.

'I was getting my nails done and a customer today was extremely rude and raising her voice at the nail salon owner for running 15 minutes behind schedule due to unexpected staff sick leave,' she wrote alongside the clip.

'The customer was verbally attacking the owner. I stayed quiet initially but the horrible customer started at her again, so l had to defend the beautiful owner.

'The customer is not always right and small business owners should not have to accept this behaviour!'

Karina's short video showed the unhappy customer was immediately defensive when questioned back.

'Don't tell me how to act. Who are you? I am talking to the business owner,' the customer said.

Karina shot back: 'So what happens if someone's sick, one of the workers, and so now they've got an overflow of customers.'

Karina (above) called out a nail salon customer for being rude to the owner

Karina (above) called out a nail salon customer for being rude to the owner

The customer said she would 'expect someone to follow up with at least a phone call'.

'Okay that's valid but it didn't come across like that. If you wanna be rude to Amy, who does a really good job, that's on you,' Karina said of the owner.

'Sometimes as business owners, things are out of their hands, such as if customers are late or early.

'I just want to make sure everyone's respected and everyone's heard.'

Commenters rallied behind Karina and praised her for standing up for the owner.

'People just need to move on if they don't like the service. Literally so many other places you can go to even if they're in the wrong! Just don't have to be rude about it. It's not that serious,' one wrote.

'Good for you! I'm so happy you stood up for Amy,' another said.

'This is beautiful, thank you so much for sticking up for her,' another wrote.

Commenters praised Karina (above) and thanked her for standing up for small business owners

Commenters praised Karina (above) and thanked her for standing up for small business owners

'Love that you stood up for the business owner. A little bit of kindness goes a long way,' another said. 

Karina told Daily Mail she hated seeing hard workers being disrespected.  

'I understand that it is frustrating having an appointment time and running behind, however, what that customer should've done was ask to speak with the owner outside or away from customers. Not in front of everyone!' Karina said.

She added the verbal assault had racist undertones.

'Small business owners should not have to face degrading comments when English is their second language,' she said.