Ofcom has fined O2 £150,000 for providing “inaccurate and incomplete” information during an investigation into problems with the operator’s billing system that concluded earlier this year.

The regulator concluded O2 had been overcharging customers over an eight-year period between 2011 and 2019. As many as 250,000 people were affected, with 140,000 paying a combined £2.5 million.

O2 was handed a £10.5 million penalty, refunded anyone who was overcharged, and changed its billing system to avoid a repeat.

O2 penalty

However, Ofcom says its investigation was hampered by O2’s “carelessness” in responding to its information requests and said it had failed to adhere to its regulatory obligations.

“We regularly make statutory requests for information from companies as part of our work to protect consumers,” explained Ofcom. “This evidence is vital to our decision-making, and so it is essential that companies respond by the deadline, with accurate and complete information.”

“Earlier this year, we fined O2 £10.5m for overcharging thousands of its customers. As part of this investigation, we requested information from O2, but it provided incorrect and incomplete responses. This contributed to our investigation taking longer to complete than necessary.”

The fine takes into account a 25% reduction because O2 admitted liability and agreed to enter a settlement. The operator has also been told to review its processes and systems for responding to Ofcom’s information requests.

O2 has been contacted for comment.

If you’re in the market for a new contract then our best O2 mobile phone deals is a good place to start