Christmas shoppers are being told to "cool it" while spending up big this holiday season after an online survey revealed a staggering number of retail staff are being verbally or physically abused.

The survey of members of the Shop Distributive Allied (SDA) union last week found 44 per cent of retail workers reported they had been exposed to abuse, and about 80 per cent of them were women.

SDA national secretary Gerard Dwyer said some of the abuse was "breathtaking".

He said verbal attacks were the most common problem but there were also many examples of shoppers physically lashing out.

"[There are] too many examples of things being thrown at people, people [trying to get] attention when they're at the deli by throwing implements into the wall behind the person serving them," he told 774 ABC Melbourne.

"You cross a line when you start to abuse people, either verbally or physically.

"We're just asking people to keep it cool for Christmas and show a bit of respect."

'The customer is not always right'

In one instance, a shopper at a large retailer at Eastland Shopping Centre, in Melbourne's east, became angry when she had to wait for a self-serve check-out with a full trolley of goods.

Shoppers need to treat staff with respect, Mr Dwyer said. ( AAP: Lukas Coch )

A shop assistant politely told the woman she could go into the store to be served by a teller but the angry shopper refused to move and continued to take her anger out on the retail assistant.

Mr Dwyer said anecdotally it appeared as though the problem was getting worse and he said the union would survey staff again after Christmas to see how it went.

He said stressed and angry customers needed to recognise poor treatment of retail staff was a health and safety issue as well.

He said increasingly busy lives meant shoppers often feel under pressure at Christmas, but that was no excuse for bad behaviour.

"What we're trying to tell the customers is that the customer is always important, but the customer isn't always right," Mr Dwyer said.

"We're just asking people though to check their language, check their temper.

"Christmas shopping can be stressful but we're there to help and we don't expect to be abused in the process."

