Issue with swapping numbers

[Luuuucyyyy]

I recently ordered a new phone and got a contract after being with PAYG for a few years. The phone I ordered (Samsung S20 FE) wasn't as I expected after using it for a couple of hours so I'm returning it.
The issue is I'd began the process of swapping the number from my current phone on to this phone before I decided to return it. It says on the website that if you change your mind, this can be resolved. While my number was transferred to the new phone, my old phone now has a disconnected sim. I messaged o2 on the live chat about swapping it back, as it says this is possible. After going through the live chat and I was told I could now use the number on my old phone, yet this was nearly three days ago and it's still disconnected.
What should I do? The phone I ordered is ready to be returned but not having a phone I can use my data on or text and phone from is a bit of a hindrance.

[Cleoriff · Accepted solution]

@Luuuucyyyy 

Just put the new sim in your old phone, as you are only sending the new device back. You should then have a working phone.

If the swap was incomplete, just keep turning the phone off and back on again until you get service.

https://www.o2.co.uk/help/device-and-sim-support/our-change-of-mind-policy