Hi Javier,
for this specific problem, only PMI is able to give you specific support with that. I understand feedback is slow, particularly via chat, but my experience is that they try to reply to e-mail within a few days. So I highly recommend to wrote them an e-mail and patiently wait for their response.
I also paid for the exam without receiving any prior notification from PMI that my application was accepted, simply based on the status of my application online. At that time, I was not required yet to choose where to take the exam. However, the online proctored mode was not available yet, so I am not sure whether the system has changed since then. In my experience, I paid the exam fee from the PMI website. Later on, after receiving an e-mail from PMI that I was able to schedule my exam, then I had to choose the testing center vs. online option directly from the Pearson VUE website. The only thing I know is that I was not allowed to reschedule my exam from a testing center to the online mode, so I had to cancel the appointment at the testing center, and then reschedule it opting for the online mode.
However - as I said - I cannot be sure if the system underwent any change, so I'd rather rely on PMI support. Just be patient and bear with them, while they will get back to you.
Gabriella
