Hi Rob,
thank you for reply. I have not resolved this with customer services, unfortunately.
I have a transcript of a chat conversation that took place back in september and the agent wrote this:
“Perfect! We’ll give you an additional £100 on top of your device value if you trade in your old phone to us. All you need to do is to complete your order and wait for the unique promotional code that we'll send to you via SMS 21 days after the delivery of your new handset.”
Unfortunately, I have never received the promotional code.
thanks