o2 do not have a live stock system, so will virtually always say in stock.
Best bet is to call customer services and ask them when they are expecting more.
Advice from an O2 Guru regarding a way to get through:
If you call 202, when it comes to 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 an advisor.
Press Upgrade, Lost/Stolen if you have to.
Numbers are in the link below.
https://community.o2.co.uk/t5/Other-Products-and-Services/Coronavirus-Covid-19-Community-Help-and-Su...
Please note, this is not customer services and we cannot access your account. Do not publish personal details (email, phone number, bank account).
Link to our guide on how to contact them can be found here