Overseas call centres 'biggest customer service gripe' for Britons
Overseas call centres are the biggest customer service gripe for UK consumers.
Which? found almost half of people (46%) were irritated by call centres based outside the UK.
Just over a third (36%) dislike automated phone systems and 32% said being passed around different people when calling a company annoyed them.
The watchdog's annual customer service survey of 3,500 people regarding 100 major UK brands found consumers rank retailers who offer knowledgeable and friendly staff and speedy service the most highly.
Which? executive director Richard Lloyd said: "Call centres and telephone systems are the biggest customer service gripes by far.
"Firms need to up their game. Those that don't give customers the care and attention they deserve risk losing out to their competitors."
The full results of the study will be released on Wednesday.