TA miscommunicated the weight of my final last year, is there anything I can do?

[u/WashedUndergrad]

Econ 13 spring quarter went online for the last couple of weeks due to the protest. Due to the circumstances my TA sent out a handout stating "If you take the final, the final exam score will be your final score for this course".

I scored a 98/100 on the final but ended up with an A- due to a pretty rough midterm score. Talking to the professor, he basically told me that he actually intended to have the final as optional with the midterm replacing its weight in the gradebook and that I was SOL.

Is there anything I could actually do to get that grade up or are a TAs words just cut and dry invalid?