Mystery surrounds what appears to be a complete outage on the Three network – and the mobile network’s website is down too.

A message on the website said: “We’re doing some essential maintenance on the site, and we’ll be back up and running soon.”

Angry Three customers took to Twitter to complain about the lack of service.

One user Tweeted: “No signal, can’t make calls or send messages since yesterday!!! How quickly is 3 going to get this sorted ??”

Other uses questioned whether Three would be compensating customers for the loss of service with one Twitter user posting: “So my network and mobile usage I’m paying for has been down for at least 3 hours now with issues earlier today as well. When will it be back up and what compensation will we be receiving?”

According to Downdetector.co.uk., people started reporting problems with Three at 11pm on Wednesday night. Reported issues appeared to slow overnight (perhaps because users were asleep) but rose sharply from 7am when about 7,845 reports of an outage were submitted.

One user claimed they had tried to call Three’s customer service only to hear a recorded message saying “there’s been a technical problem, try again later”.

A Three spokesperson said: “Following technical difficulties with our services across voice, text and data, some customers will be experiencing an intermittent service. Our engineers are working to fix the issue and the service is returning to normal, and we expect it to be resolved over the course of the day.

“We advise our customers to turn their phones off and on or turn airplane mode on and off, which may resolve the issue. We are sorry for the inconvenience caused to our customers.”

Adam French, Which? consumer rights expert, said:“Huge numbers of Three customers have woken up to find they are unable to make calls or use roaming data and will be left feeling angry and frustrated as a result. The mobile operator has to do right by its customers by keeping them informed, ensuring no one is left out of pocket and we expect those affected by this lengthy lack of service to be compensated.

“The UK is already lagging behind the rest of the world on the provision of 4G. Failures like this will only intensify the pressure on the government, industry and the regulator to up their game and ensure we get a decent service.”

The outage is the second major issue to affect a mobile network this week. On Monday Vodafone customers overseas complained of being told they owe the network thousands of pounds in incorrect charges and would have service halted until they paid up.