For its landline services, TalkTalk Group averaged 1.78 complaints per 1000 customers between October 2010 and February 2011.
Its landline complaints reached a peak in November, following an Ofcom investigation into the company incorrectly billing customers for services they had cancelled.
TalkTalk also topped the complaints list for broadband services. It received 1.27 complaints per 1000 customers for the period.
Virgin Media was the least complained about provider for both broadband and landline services. It received 0.20 and 0.21 complaints per 1000 customers respectively.
Among mobile providers, Three UK was the most complained about company, receiving 0.15 complaints per 1000 customers.
O2 was the least complained about mobile provider.
Ofcom says it receives about 450 telecoms complaints per day on average, on issues ranging from mis-selling to lack of service.
For more information, see the tables below