Suspicious text regarding my 'plan'

[Ren24]

Not sure if this is the right place to post this as I am not even an O2 customer, but I received a text from what shows up in my phone as 'O2UK', confirming my 'new' number, which I have had for years, and a custom plan with 20GB, unlimited UK minutes and texts.

I then almost immediately received a second text addressing me by a name that is not mine, telling me I have placed a £60 spending cap on my account.
I am not and have never been a customer of O2, and I have had this particular phone number for what must be 10 years. I do not have the option to reply and I can't see what number the message came from, it just shows as O2UK. I'm not sure if this is a case of an incorrect number or if this is a scam. Since there are no links or codes of any kind in the text and I can't reply, I am assuming it is the former, but would love if someone could confirm and what I should do from here if that is the case.

[MI5]

@Ren24 

You need to contact O2 to check there's no fraudulent activity connected to your number.
All numbers are in this guide Guide: Coronavirus Community Help and Support 
When you call, you will be asked for the reason you are calling.
Stay silent for 15 seconds and you will be taken to the keypad options.
Press 2 for Everything Else
Press 5 for More Options
Press 7 for Anything Else which will put you though to someone.
You can also try saying "Upgrade" or "Fraud" to be connected to an advisor.
8.00am is the best time to call if you can.