S23 256 GB + Galaxy Buds 2 Pro + 50GB Data with rollover £280 upfront £23.99 p/m 24 months £855.76 @ Carphone Warehouse

Read the terms, sounds like it's paid on top once it's confirmed OK (though oddly does state the S23 Ultra). £130 is the price anywhere will give you on trade-in so figure it must be £100 on top of that:

Buy the Samsung Galaxy S23 and get £100 on top of your trade in value when you trade in an eligble phone

Terms and Conditions (CPW): Initial Trade-in value will vary dependent on device. Offer available when you trade in online and in store and continues until 31/03/2023. Additional discounted values only apply when you trade in any eligible handset and purchase a new Samsung S23 Ultra. Trade In value and additional promotional value discounted off the upfront cost of your phone when you buy in store, or via BACS transfer if online, or if the trade in plus enhanced value is higher than the cost of the device. For online, your promotional amount will be paid as a separate transaction once we have assessed you qualify for the promotion, your trade in device payment will be paid on receipt of the device. If the device is bent, broken into pieces or any of the internal parts are showing, it is classed as 'Beyond Economic Repair' or BER. A device that is BER or has ZERO value and cannot be traded in. For online trade in, a promotion form for further information will be provided through a confirmation email. This form must be completed in order for promotional payment to be made. Offer not available in conjunction with any other offer. Subject to availability.

So did it show you at the end of the deal you'd get the extra £100 on your S10? There seems to be some confusion as to whether the price they quote (i.e. £130 for an S21) includes or excludes the £100 bonus trade-in...

Yes but £365 upfront payment !

It seems the deal has expired

I missed out on a great S22 deal for that reason pre xmas. Still not sure if I want to swap to 3