A cyber attack on the TalkTalk telecoms group in October cost the company as much as £80m but fewer customers than feared opted to end their subscriptions.
Chief executive Dido Harding went on television and radio in the days following the hack to warn the company's 4 million customers that their financial data had been put at risk.
The numbers affected turned out to be far fewer, with limited data stolen from about 157,000 people, but the bad publicity did cause a spike in defections.
"We saw a big dip inevitably in early November and then the business started returning to normal through December and very much back to normal now," Harding said today.
Five young men aged between 15 and 20 were arrested and freed pending further inquiries, police investigating the attack said last year.
A total of 101,000 customers left the company - less than 3% of the subscriber base.
Bigger rivals Sky and BT benefitted from TalkTalk's problems, adding 144,000 and 130,000 broadband customers respectively in the last three months of 2015.
The financial costs of the attack included a one-off £40-45m, and a £15m impact on trading in the third quarter to the end of December.
There would also be £20m hit from the reduced customer base in its final quarter.
Harding said she was ready to take advantage of any remedies imposed by European regulators vetting a deal to combine mobile operators O2, owned by Telefonica and Hutchison's Three.
TalkTalk has a wholesale agreement with O2.
"We think the Commision has two choices, either to block the deal outright or to create a fourth mobile operator," she said.
"Should they choose to create a fourth mobile operator, yes we would be interested in looking at that," she added.
She declined to say if she would do a deal with a partner, such as France's Iliad, which is also reportedly interested in opportunities arising from the deal.
