VIRGIN Media and O2 have introduced a way for customers to have a single ID login to access both accounts.
It's designed to make customers' lives easier, but some fear it will "only end in confusion".
Since 14 November, customers who have accounts with both Virgin Media and O2 have received emails inviting them to create an online ID that can be used interchangeably between both accounts.
The joint ID can't be used to sign into the individual apps.
And customers won't be able to unlink their accounts once a joint Virgin Media O2 ID has been created.
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However, customers can continue to sign in with their old credentials if they choose to - for now.
The company has noted that the ability to use old credentials is only "temporary".
The move comes more than two years after Virgin Media and O2 merged into one company.
In an FAQ, the company wrote: "We’re on a journey to becoming one company – Virgin Media O2.
"Temporarily your old My O2 sign in details will still work whilst we update all our services, but in the future they’ll be disabled.
"Once you’ve linked your sign in details to create a Virgin Media O2 ID, start using these to avoid any issues.
"That way you’ll benefit from only needing one set of details to sign in to Virgin Media and O2 online spaces.
"Plus, in future you’ll be able to use new security features such as biometric and single sign-on authentication, for added online security."
But customers are unsure about the change.
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"Sounds good on paper but having implemented SSO services, this will only end in confusion for months. But it is a step in the right direction," one customer wrote in an O2 community forum.
Another wrote: "Our house has VM and I am on O2. I have credentials to log into My o2 (app and online).
"I also have credentials to log into my VM account (app and online).
"If I create a new merged account I can log into both online, but not the app.
"That's just ANOTHER set of logins to 'remember'."
Virgin Media answers customers' most burning questions about the change here.
A Virgin Media O2 spokesperson said: “As part of our plans to improve the products and services we provide, we have started to roll out Virgin Media O2 ID, simplifying how customers can access our services online by giving them the option to create one set of login details.
"We’re continuing to invest in our online services and will be rolling out further features to improve our customer’s digital journey and provide additional layers of security."
