A handful of licensees in south Wales are angry with Scottish & Newcastle UK (S&NUK) after reporting major problems with deliveries.
The licensees from the Brecon area say problems have occurred after S&NUK bought SA Brain's distribution service two months ago, trading under the name Heineken Wales.
Host Marilyn Price said S&NUK failed to deliver correct fonts for big sellers Brains Dark and Foster's in time for the start of last weekend's Brecon Jazz Festival.
Price said the company also failed to collect its barrels after she cancelled her supply contract last week, which meant an alternative supplier had no space to deposit containers.
The freehold licensee of the Camden Arms in Brecon said she ran out of lager on Saturday, costing her at least £1,000.
"It really ruined the festival for me," she said. "We work hard to get the jazz festival up and running and we had this added stress of not being able to dispense the beer."
John Harries, secretary of Brecon Licensed Victuallers Association, said around six LVA members had told him they'd cancel their contracts if the situation didn't improve.
He said problems have included S&NUK insisting on payments being made by direct debit and being less flexible in deliveries.
The licensee of the freehold Three Horseshoes Inn at Llanfaes said: "I've stopped dealing with [S&NUK]. They called at 6.30pm on Friday for the order for the week. They don't know the area and they're not au fait with the customers."
He added: "All the licensees I've spoken to want to have a meeting to sort it out, or they will drift away."
S&NUK: 'We will act'
A spokesman for S&NUK said: "We are aware that some customers in the Brecon area have experienced some service issues over the past week. This is a situation that we take extremely seriously and we will be meeting with representatives of the local LVA to address their concerns, and seek to improve our service where it has failed to meet our high standards."