Two of the countries biggest telecoms firms have refunded customers a total of £2.5million.
Ofcom received more than 1,000
complaints but estimated that up to 62,000 people had been affected.
The complaints were normally about aggressive demands for the payment of
bills that customers simply did not owe.
TalkTalk passed the buck to a new billing system that was introduced after it bought over Tiscali in 2009.
The two firms that have 4.2million customers have taken numerous steps to fix the problem.
The average refunded to customers is around £40.