Three has been fined £250,000 for failing to handle customer complaints correctly.
Ofcom issued the fine to the mobile operator after discovering numerous problems with Three’s complaints procedures.
In some instances the company closed complaints that had not been resolved and in others failed to log complaints made.
Three also failed to inform customers, either on the phone or in writing, of their right to escalate complaints to the independent alternative dispute resolution services.
Communications firms are legally obliged to make customers aware of this service, Ofcom noted.
Ofcom said that Three had been cooperative throughout the investigation and had now put processes in place to improve its complaints handling procedures.
However, Claudio Pollack, Ofcom’s consumer and content group director, said that a fine was necessary to underline the seriousness of the case.
“When things go wrong, customers are not only entitled to complain to their provider, but must have confidence that their complaint will be dealt with fairly. That’s why we impose strict rules on providers on how they must handle complaints," he said.
“The fine imposed on Three takes account of the shortcomings in its complaints handling, but reflects that the harm to consumers in this case was limited.”
Three must pay the fine within 30 days.
In response to the fine, Three said that it takes customer complaints seriously and now has processes in place which should that ensure no such problems happen again.
“Ofcom identified issues with our complaints handling process back in spring 2013,” the firm said.
“Since then we have worked closely and openly with Ofcom to address these as part of the broader effort to improve complaint resolution, contacting all the customers that might have been impacted.”
Three also touted the fact that, based on Ofcom’s own data, it is the least complained about mobile operator in the UK this year.
The regulator is taking an increasingly tough stance with firms that breach consumer protection rules. Last year it fined TalkTalk £750,000 for nuisance calls to potential customers.
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