The telecommunications industry regulator has launched an investigation into billing errors by phone firm BTC that led to business customers being hit with extra charges for services dating back a year.

The Regulatory Authority stepped in after members of the public complained about back charges due to a billing error by BTC dating to last October.

Thousands of businesses were hit by the unexpected extra charges.

A RAB spokesman said: “The authority is currently investigating the matter and is advising customers who dispute the charges to do so in writing to BTC at request@btc.bm.

“In accordance with BTC’s terms and conditions, customers are not liable for disputed charges until the dispute is rectified.

“However, customers do remain liable to pay all undisputed charges to avoid disconnection of service.”

The RAB will announce the results of its findings at a later date.

Customers who do not receive a response from BTC can notify the Authority via its website at www.rab.bm.

The billing error comes after BTC earlier this month hit some business users with an $800 extra charge on their November bills to cover a “usage billing error backcharge”.

A spokesman for the firm said then there had been “an issue” with a third-party system, which meant some bills were worked out on the basis they had 100 inclusive calls instead of 50.

But the spokesman said that the problem had been “fully rectified”.