Thank you so much for your first post to our Community Forums and welcome to the team! It's great to have you here!
I'm so sorry for nay confusion this my have caused! To clarify:
If you are within your 14 day cooling off period then you can can cancel your current SIM and order the Oomph one.
You can also cancel the SIM you have now to use the Oomph one alone, but if you are in contract this may incur early disconnection fees. You will also need to call us on 0345 600 0789 or text us on 07533016422.
You can also read this forum post on how we could help should you not wish to cancel the current SIM you have, which you can view here.