TalkTalk has estimated that last month’s cyber-attack will cost the company £35m and has announced that customers can apply for a free upgrade to their service.
The Internet service provider said it was offering the upgrades in ‘recognition of the unavoidable uncertainty’ that customers faced after hackers obtained their personal data.
Although it was initially feared that 1.2 million customer details were stolen, after extensive investigation, TalkTalk concluded that 156,959 customers had had their personal data compromised and only 15,656 bank account numbers had been taken.
Chief executive Dido Harding said: "TalkTalk takes the security of customers' data extremely seriously and we are taking significant further steps to ensure our systems are protected, as well as writing to all our customers outlining what we are doing to keep their data safe.
"In recognition of the unavoidable uncertainty, and because we know that doing what is right for our customers will ensure the best possible outcome for the company over the longer term, we are today announcing the offer of a choice of free upgraded services to all our customers.
"Over the course of the last three years we've spent a third more on security and I can absolutely guarantee that going forward we will spend much more again."
TalkTalk confirmed all its customers, not just those affected by the hack, will be able to select an upgrade from December 1.
Although the company believes it is too early to assess the wider impact of the cyber-attack on the business, the estimated one-off financial cost of £35m included the loss of online sales and services.
The firm said last month it will only waive termination fees for customers wanting to end their contracts if money is stolen from them.
A parliamentary committee is conducting an investigation into the circumstances surrounding the breach and the wider implications for the security of personal information online. The House of Commons culture, media and sport committee will start taking evidence later this month.
Shares in TalkTalk plunged in the wake of the hack, but have since bounced back by as much as 12 per cent after the company's reassurances.