Network Problem caused my future

On the 25th of November 2020 I was due to write an online examination and failed to because there was no network. When the network came back I contacted the institution because I had missed the examination,they advised that I call my network provider for proof that there was no network coverage. I did that on the 30th November 2020 and was given feedback yesterday 02 December 2020 that since I did not call in on the 25th of November they won't be able to assist. How was I going to call cause all of us in the house are using Vodacom network and we all did not have network coverage to contact them and due to frustrations when the network finally came back I contacted the institution and did not think of Vodacom. The whole of last week there was a network problem with Vodacom at Kriel town in Mpumalanga and this was not experienced by me alone.I got deeply affected cause I had to miss an examination and no one wants to assist with a letter stating that.