How to cancel monthly subscription to photoshop?

I am trying to cancel my subscription, and on top of that being told that I have to pay 50% of my yearly even though I signed up for monthly Due to tech issue on my end the product is just not working to it fullest for me. I'm got in touch with billing and tech support and even though they pulled up my account when it came time to cancel they "ran into technical difficulties" and couldn't find my account to cancel. Can someone please help me with this case. Thanks