@Madmam1To cancel the order you would need to reject the delivery at your door, and wait for it to be returned to o2, and the contract being cancelled, before starting again in store.
It sounds like UKMail, have staff off sick, hence the delivery has been put back to Monday, you could always ring your local depot to see if you could pick it up (if they have it).
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iPhone 16 Pro Max - o2 and Spusu
Xperia 1V - Spusu
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This is not customer services and we dont have access to your account
I do not work for o2 or any VMo2 /Telefonica/Liberty Global Company