Which perk was it? If you had difficulties with self-serve, a rep might be able to assist on the forum here.

The unlimited long distance calls, I've even tried not selecting any perk and change them, but nothing works 

Hi there ​@Oscar80 

Can you try to clear the cache and cookies of your current browser or try a different browser or device, if possible and test ?  After these steps, try to change the perk and skip the perk selection / continue without selecting a perk. 

Let us know how it went. 

I already tried all you have said, even 2 different devices, that I never logged in before, and I still receiving the same error 

Got it. In order verify additional information  we have sent you a private message. Feel free to respond whenever you have the time.