Istqb Pearson - Exam cancelled by proctor saying mobile hotspot connectivity is not allowed

My online exam was scheduled for today evening (**/**/**** at *:** PM). I started the checkIn process and uploaded all required images and id card pictures.

*-* Minute later one of the proctor contacted me and she asked me to show bed and desk, I showed it to her.

She asked me to remove my mobile from the bed/room: I told her that my laptop internet is connected from a mobile hotspot. She said that internet connectivity is prohibited or not allowed from mobile hotspot and invoked my exam.

Even I said that I put my mobile in front of the camera or I was ready to put out of room but later on she only forced me to change internet connection.

How will candidates give an online exam if they use only mobile hotspot for the internet? I do not have other options for internet connection.

I was not aware that hotspot connectivity is not allowed for the exam even when I ran the system test there were no such messages and it is not mentioned in the Admission policy too.

She shared me a case number and asked to speak from customer care:
Please look into it.