I got a message which says "Hi, just a quick update to let you know your request to transfer your number to your new giffgaff SIM is underway. It should be completed within 24 hours." In the first post I explained to you my experience so please help me with my original SIM card.
The confusion has been caused by you apologising for ordering a SIM card. If your SIM has been deactivated, it cannnot be reactivated.
On the assumption that you have neither ordered a SIM within the last few days, nor requested a SIM swap, then it appears that your account has been accessed without your permission, and your number hijacked by fraudsters.
If you received a text message recently saying your account had been suspended, and you clicked on a link in that messge and provided a lot of personal info, you need to take immediate action to secure your account.
Change your password on all other sites that use your email address and password you used on giffgaff. Do not use the same password on more than one site;
If you have a spare (unactivated) giffgaff SIM card, do a SIM swap (activate new SIM whilst logged into your current giffgaff account. If you do not have a spare SIM and are in the UK, report your SIM lost/stolen here: https://giffgaff.com/support/lost
If your bank/credit card details were saved on your account, contact the card issuer and alert them to the potential of fraudulent activity on your account.