BT has been told that it must repay its corporate customers after overcharging for ethernet services.

Watchdog Ofcom said that British telecoms operator faces a $154.19 million refund to communications providers BSkyB, Talk Talk, Virgin Media, Verizon UK and Cable & Wireless.

Ofcom received the first complaint that charges levied by BT for high-speed data services were "not cost orientated" in 2010, and continued receiving related claims before issuing its final determination on the dispute on December 20 2012.

BT can appeal the decision over the next two months but it is not good news for the company which has had a tough year.