@kholoudmanlucu god bless you in your coming exam. I'm located in the Philippines and it has one center accredited by PTE-A... there were 2 centers few years back but I reckon that the other one had more mic issues since majority seem to fail more there (just an observation based on numbers) ... prior taking pte exam, I called up PTE center in makati to inquire the brand of headset and keyboard which they were currently using... It seemed that they do not disclose this info. Having that small info meant that I wont be worrying about adjustments in terms of typing and utilizing the mic of the headset.... However when I took the exam last tym, thats the only time I knew that they were using a standard Logitech keyboard and Plantronics Audio 655 USB Multimedia Headset with Noise Canceling Microphone

Im not sure about the model of the plantronics wired headset but I'm certain that the headband has a reverse orientation which was uncomfortable since I'm wearing glasses, and has a volume adjustment on the left speaker side which was not clearly indicated if it was for speaker or mic volume by the invigilator... (based on the manual i recently read, it was for the speaker volume adjustment and this meant that there was no means of adjusting mic volume from external physical switches of the headset...)
Regarding not clicking "next" after recorded answer is generally okay. However if the recording continues after 3 seconds of silence, this might be a mic adjustment issue. i guess mic volume plays a big factor particularly capturing background sounds or even ur breathing sound after saying your answer to the mic. With this, computer also analyses these sounds as bad pronunciation and low oral fluency which lowers the overall speaking score. I know it may sound peculiar and defensive but i think these are some of the limitation of computer assessment which is based on software. Despite of such, I believe this is better than those ielts examiners who are forced to fail some exam takers for the sake of putting more income to their business.
I really hope PTE should also be available in cebu or davao to avoid flying to manila to take the exam.