Hi, are you seeing an error message when you put in the 6 digit activation code?
If so, what's the full error message
Are you a new or returning customer
An existing customer and activating a replacement sim after reporting your previous sim lost
Or performing a sim swap?
Did you order the sim from giffgaff.s sim order page
Did you obtain it from a store or shop
Did the sim arrive with a phone purchase from giffgaff?