Hi Ian. Welcome to justanswer.
No we cannot activate that for you. But I will guide you through to update the Microsoft account details in app store.
Now update your new card. Reply for further assistance.
On the Start screen, tap or click Store to open the Windows Store.
Tap or click Account, and then tap or click My account.
Tap or click Add payment method or Edit payment method, edit any necessary info, and then tap or click Submit.
Now update your new details.
You have downloaded the copilot app from the app store?
On your phone, go to the store and see if the details are of old credit card or new.
Okay uninstall that app from your phone. Again install it from the store and then register with the new email and other new credentials.
Try that and see if it works or not.
Do rate the chat positively (You need to click the 5 stars present on the upper panel). If problem is still there then reply for further assistance.