Why on Earth would you assume a refund is out of the question? You purchased tickets under the condition that the performance time was 7pm. They changed it, and now you are entitled to get your money back or exchange to another performance.
"The Spectacle has, indeed, an emotional attraction of its own, but, of all the parts, it is the least artistic, and connected least with the art of poetry. For the power of Tragedy, we may be sure, is felt even apart from representation and actors. Besides, the production of spectacular effects depends more on the art of the stage machinist than on that of the poet."
--Aristotle