TalkTalk, the telecoms firm that was hit by hackers last year, said its customer numbers slipped in its first three months of the year.
The company, which also provides online and pay-TV services, said group revenue was 0.4% lower after it lost 9,000 broadband customers in the three months to 30 June.
However, it reiterated its previous guidance that full-year earnings would "grow modestly" to between £320m ($419m, €381m) and £360m.
It said programmes to upgrade its systems and make its billing simpler are "gaining real traction in driving an improved customer experience".
The group, which has around four million customers, added it was on track to make savings of between £35m to £40m by the end of the year.
TalkTalk saw its pre-tax profits halve last year, to £14m, after one of the highest-profile cyberattacks in UK corporate history last October affected 156,000 of its customers.