Final year exam

So guys, I sat my university final year last exam yesterday. As the general rule for students writing exams; your bag should be in front of the class, don't have nothing on you that can be used against you for exam malpractices and all that. Before we commenced writing, the invigilator came to me with a bag to put my phone in if I had my phone on me, which I did. It didn't occur to me that I've not switched off the phone which I normally do before writing any exam. Fast forward to an hour into the exam. My phone which was sealed up in a bag on my desk vibrated. The invigilator came to me asked me to switch the phone off which I was expecting anyway. I told him I'm sorry I thought I switched the phone off, which was a genuine mistake. Then the guy told me I'm foolish, with a lot of anger all over his face, if he could hit me, he probably would. He took my student ID, walked to the other invigilator in front of the class and said to her that I should be failed! I'm sure other students in the room heard him as well. As soon as he said that I was mortified and distressed at the same time. I couldn't write a word more out of shear fear that I'm going to be failed. I submitted not long after, the other invigilator followed me outside and said that they will have to inform the exam board about what happened. I asked her why and she replied "Because your phone vibrated three times" And said they were going to inform the examination regulation board about it. I'm still very much confused, my phone vibrated, that was it! Nothing else.