Wrong theme & didn't realise there were monthly charges

Hi There, when I purchased this theme, I didn't realise it was a monthly charge, I thought it was one off.

I stupidly purchased this at 11pm at night (in Aust) and after viewing the live preview through WP realised that it was not the actual theme that I wanted after all.

My questions are: 1. can I cancel this purchase &/or 2. is there any possibility of changing over to another theme instead?

Many thanks for your time.

Nicole