Demonstrator messed up my practical and I got 0 marks

I had a lab practical two days ago which involved setting up a lot of equipment with my partner. We had a demonstrator (like a lab assistant) come and oversee the setup. At one point, we screwed the lid to a container on really tightly and she told us to “not do it so firmly and leave it a bit loose” and even loosened it for us.

About an hour and a half later when we were getting our results, we noticed that ours were completely wrong and called our lecturer over. He fiddled with the equipment and said “your results are wrong because you didn’t screw the lid on tightly.”

When my lab partner bought up that we had been told to keep it loose by a demonstrator, he sort of laughed at us and said “I bet she didn’t.” So he basically accused us of lying.

We had to go all the way to step one of the experiment and were an hour and half behind everyone else. By the time we got our results, we had about five straight minutes to complete an entire report. We only got like 5 sentences down and I found out the next day that I’d been given 0 marks for my report.

I talked with the lecturer about it and he told me to stop panicking and that it was “only a tiny portion of the grade.”

Is this fair...? That my experiment was ruined by one of HIS demonstrators, leaving me very little time to complete my report and thus awarding 0 marks?

I had a lab practical two days ago which involved setting up a lot of equipment with my partner. We had a demonstrator (like a lab assistant) come and oversee the setup. At one point, we screwed the lid to a container on really tightly and she told us to “not do it so firmly and leave it a bit loose” and even loosened it for us.

About an hour and a half later when we were getting our results, we noticed that ours were completely wrong and called our lecturer over. He fiddled with the equipment and said “your results are wrong because you didn’t screw the lid on tightly.”

When my lab partner bought up that we had been told to keep it loose by a demonstrator, he sort of laughed at us and said “I bet she didn’t.” So he basically accused us of lying.

We had to go all the way to step one of the experiment and were an hour and half behind everyone else. By the time we got our results, we had about five straight minutes to complete an entire report. We only got like 5 sentences down and I found out the next day that I’d been given 0 marks for my report.

I talked with the lecturer about it and he told me to stop panicking and that it was “only a tiny portion of the grade.”

Is this fair...? That my experiment was ruined by one of HIS demonstrators, leaving me very little time to complete my report and thus awarding 0 marks?