Millions of Lycamobile customers have been moved from the O2 network over to EE - but many have claimed the switch has affected their signal.
Lycamobile - which has 16 million mobile customers globally - used to piggyback off the O2 network in the UK, but has now signed a new deal with BT, which owns EE.
If you’re a Lycamobile customer, you should still be able to use your phone as normal - but it will connect to the EE network instead of O2.
However, consumer rights website MoneySavingExpert.com has reported complaints from some customers, saying they’ve been struggling to use their phones over the last few days.
Lycamobile informed customers by text and email last week that it would be upgrading its network, but MSE said this notification did not mention the move to EE.
Customers were said to have been told they "may experience occasional disruptions during this time" and were advised to restart their mobile if they experience issues.
However, some users said this did not help restore their network.
One person tweeted: “My network is down since yesterday, can you tell me please how long the network upgrade will take?”
Another said: “Facing network issues after the recent network upgrade. No network coverage on my mobile. Have restarted the mobile as well. Still not working.”
A third tweeted: “What is happening with the Lycamobile network? I can't make any calls.”
Ofcom rules state you may be entitled to compensation or credit on your account if you’ve been left without signal for a long time.
In the first instance, you should contact Lycamobile. If your problem isn't resolved after eight weeks, you can then escalate your complaint to the Communications Ombudsman.
The Mirror has contacted Lycamobile for comment.
In its press release earlier this week, Lyca Group chief executive Richard Schäfer said: "Network performance has become a vital concern for mobile users in a competitive market.
“Through the EE network, Lycamobile customers will not only enjoy the low-cost services we're famed for, but will be able to enjoy super-fast connectivity and improved coverage."
Alex Tempest, managing director of BT Wholesale, added: "Thanks to this partnership, Lycamobile customers will receive access to EE's 4G and 5G network, which currently supports data speeds that are around four times as fast as what they received previously."
