You'll need to call customer service.
Numbers here Guide: Coronavirus Community Help and Support
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 someone.
Say "Upgrade", "Lost/Stolen" or "Fraud" if you have to, to get put through to someone.
8.00am is the best time to call if you can.
If the o2 shop page says out of stock or delayed by x weeks now and you have an order delayed email then you will have to wait until o2 gets stock in I have just experienced this farce again with my iPad order the same and the 6 weeks they estimated was almost correct .
O2 really needs a live stock system and not end up disappointing customers, who start with the in stock on the shop page complete upgrade or purchase only a few hours later to get the dreaded out of stock email!!