Customer complaints about telecoms and pay TV suppliers have increased, with EE and Vodafone retaining their positions as the most complained-about companies.
Ofcom said it was "disappointing" to see a rise in the number of complaints between July and September after several months of decreasing figures.
EE and Plusnet attracted the highest volumes of landline complaints at 34 and 33 per 100,000 customers respectively, mainly relating to faults, service, problems with changing supplier and complaints handling.
BT, Post Office HomePhone and TalkTalk also continued to generate landline complaints above the industry average of 17 per 100,00 customers.
EE again attracted the most complaints for fixed line broadband, while Plusnet and BT saw significant increases in complaints, and grievances about Talk Talk remained higher than the industry average.
Vodafone remained the most complained about mobile provider after its numbers increased from 14 complaints to 20 per 100,000 customers, mainly regarding billing, pricing and charges, complaints handling and concerns around faults and service.
EE was the only other mobile provider to generate more complaints than the industry average of eight per 100,000 customers.
Tesco Mobile generated the lowest volume of complaints among mobile providers for the seventh consecutive quarter.
BT became the most complained-about pay TV provider over the third quarter, with numbers increasing significantly from 11 per 100,000 customers to 25.
The only provider to generate fewer complaints than the industry average was Sky, which remained the best-performing pay TV provider.
The regulator said it receives just under 300 telecoms complaints a day from consumers.
Claudio Pollack, director of Ofcom's content and consumer group, said: "We expect providers to make customer service and complaints handling top priorities, so it's disappointing to see a rise in the number of complaints.
"Consumers have a right to expect good service and will rightfully complain when that standard isn't met.
"Ofcom is continuing work to make switching easier and our complaints data allows consumers to make meaningful comparisons that can be useful when looking for a new provider."
A programme by Ofcom to monitor providers' complaints handling procedures has led to separate investigations into Three UK, EE and Vodafone.
Ofcom fined Three UK £250,000 in October last year, and fined EE £1 million in July this year for failing to comply with rules on handling complaints.
The investigation into Vodafone is continuing.