Your post is unclear.
What application/request are you referring to that you want cancelled?
If it's a replacement SIM request and you chose the "block my SIM" option then I don't think that this can be undone and you'll probably have to wait for the replacement SIM to arrive and activate and use that when it does.
If it's something else then please clarify what you're referring to and what exactly you want done.
If you need to contact 48 support about this then see the links in my signature below.
