refund

Hi, I opted for a free trial and was charged before the trial ended. I tried to contact prezi but kept getting told that i needed to have a pro account to get premium support. Whilst trying to obtain help my account was upgraded which is not what i wanted. I cancelled it straight away yet now have been charged not once but twice. This is extremely fustrating as I am not even using prezi. Please could I have a full refund. Feel very dissatisfied with prezis customer service :(

Kind regards
Aameena