In the aftermath of the cyberattack on its website in October 2015, thousands of TalkTalk customers abandoned its service and switched to alternative telecommunications companies. According to market research firm, Kantar Worldpanel, TalkTalk's share of new customers in the home services fell by 4.4% when compared to the previous quarter before the data breach.

Apart from losing new acquisitions, the telecoms company also lost existing customers in the fourth quarter of 2015, with about 7% of users turning to different providers.

Imran Choudhary, consumer insight director at Kantar, said that, "Customers have lost faith in TalkTalk as a trustworthy brand."

"TalkTalk continues to offer some of the most attractive promotions across the home services market and almost a third of its new customers did choose it for this reason, but there can be no doubt that it lost potential customers following the major data hack. If it's to recover from recent events TalkTalk will need to offer more than just good value," he added.

About 250,000 broadband customers left the company, Kantar told the Register. Despite the company gaining 100,000 more customers in the days following the hack, the net loss of customers comes up to 150,000. Kantar also said this loss in the fourth quarter was larger than compared to other broadband providers combined. TalkTalk has about four million UK customers overall.

Other UK telecoms service providers

In the same quarter, BT was the biggest winner, claims Kantar. It gained 40% of its lost share, with about a fifth of those who left TalkTalk switching to BT. It performed quite well in the last quarter of 2015 and enjoyed strong growth in terms of TV and broadband customers. It garnered a 30% share of the broadband market, outpacing Sky UK, which is its biggest rival.

"In contrast to TalkTalk, BT felt the benefits of an improved perception of reliability, with 12% of new customers saying their primary reason for joining was because they saw it as a trusted supplier – twice the market average," Choudhary said.

Sky lost new acquisitions in home services during the last quarter, as a result of weaker performance in the broadband service. However, it still remains the second largest broadband provider after BT and dominates the TV market as well, occupying 40% share of the market in the three months to 31 December 2015.

Among others, Virgin Media made a small gain in the broadband sector while its share dropped in the TV market by 6% than in the previous quarter.