TalkTalk's hack will cost it £35 million

Internet provider TalkTalk said the theft of customer details would cost the company as much as £35 million ($53 million) in a one-off hit.

TalkTalk also said it would offer all customers a free upgrade to their services "to ensure the best possible outcome for the company over the longer term."

Half-year revenues were up 4.7% in 2015, the company said, allowing a dividend hike of 15%.

Here's what CEO Dido Harding said in TalkTalk's half year results statement on Wednesday:

We have recently been able to confirm that far fewer people were impacted by the attack than originally feared. However, 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.

The cyber attack on TalkTalk happened on 21 October, with hackers stealing the bank details of more than 15,000 customers. They were able to access the personal details of more than 156,000 people. Four individuals have been arrested in connection with the hack.