@amalirobe What error are you getting? can you post the exact error message? Also, it might contain an error code, that can tell what kind of error is that
And is porting involved in the activation? if so, what information of the old carrier did you try to put in? If you have been putting in IMEI number, maybe try changing to Account number of your old carrier.
Also, before you try activating again, make sure you check your credit card that PM has not got the money out from your credit card yet