Marked down for this - but was I correct?

I was in college today and the teacher gave us all an assignment; write a letter to a company informing that you have a problem with their product.

I started mine somewhat similar to this -

I recently purchased a Ridalto Zoom 35mm camera from Hampus Direct earlier this year.

Very pleased with my purchase, I continued to use it until it was time to develop the film, and that was when everything turned sour.

She marked me down because I started the sentence with "Very pleased" instead of "I was very pleased with my purchase."

I was writing it in the third person, another example would be - "Ecstatic with my gifts, I ran upstairs as fast as I could to revel in the joy thus provided."

I discussed it with her and she was 100% sure I was incorrect, I discussed it with my friend studying English Literature at Portsmouth University and he said mine had a better flow and he doesn't see why it would be incorrect.

Anyone wanna chime in?

Thanks,

Sam.