I signed up to the free trial in January and cancelled it shortly afterwards. I just noticed I have been charged for the past 3 months and when I try to cancel Adobe want to charge me more. Is there some kind of hidden terms and conditions of the "free" trial and can I get a refund? I haven't used any of the photos either.
I also installed a free trial of Adobe Acrobat Pro for a ffew hours2 weeks ago and cancelled that on the same day. Will I be charged for that now as well??
The 30 days trial converts automatically in an annual subscription as described in the conditions you have accepted at the time taking the subscription. Cancelling after that date will give you a refund if you cancel in the first 15 days of the paid subscription. Passed that date, you have agreed to an annual subscription. Cancelling an annual subscription will charge a fee of half of the remaining due.
These terms are not hidden, you explicitly checked a box that you read and accept the conditions of this. Also: you are paying for the service to be able to use your allocated number of assets, like a phone subscription where you may possibly use your contingent but when you decide not to use your phone at all, you get invoiced anyway.
This said, you may try your chance and negotiate your way out of the contract with little or a lesser fee by contacting Adobe Customer Service: Adobe customer care can be contacted here: https://helpx.adobe.com/contact.html - click the small callout at the lower right of the screen and type "agent".
As of your second question: if you have cancelled immediately you will not be charged. Even if you would not have cancelled you would have the same 15 days grace period to ask for a refund.
https://account.adobe.com tells you about the current status of your subscriptions. Be sure to check that. You may also ask the support agent if your Acrobat trial is cancelled for good. You will get a transcript of your chat session if you tick the check box. Otherwise, with the case number you get attributed, an Adobe employee can check the case and what has been done to solve your problem.
Regards, Abambo Hard- and Software Engineer and Photographer.