If a company offers you a free trial, it is not free if they need your credit card number. The $1 dollar sounds good, but it is really just a way of buying your credit card number. Once you give it to them, they will commence billing you. Usually you can't reach them by phone or email to cancel. However, cancelling with them is what you must do. DO NOT GIVE OUT YOUR CREDIT CARD NUMBER TO ANYONE, UNLESS YOU KNOW EXACTLY WHO YOU ARE DEALING WITH. If you have exhausted your efforts to contact and cancel with the so called merchant, then contact your cc company. Write down dates when calls were made and who you spoke to. Also keep copies of any emails, either from you to them or vice versa.
Remember, there is no such thing as a free trial of anything. They (whatever company or merchant) will always ask for your cc number. Usually they say it is just to bill the shipping and handling, or whatever. Another precaution, always read all of the disclosure provided very carefully. You may have to read between the lines to see that they are actually saying they are going to bill you or sign you up. For example one vitamin pill provider for weight loss, says "if you get the free trial of A, we are also going to give you a free trial of B and C as well." What that means is that "we are also going to be billing you for two other products as well." You end up having 3 monthly charges on your cc, and B and C show up as separate merchants, with separate phone numbers. You cannot cancel B and C, by getting in touch with A. You have to call each one individually, and often they are impossible to reach. Any time you are not able to make contact with a merchant you gave your cc number to, especially if it is a "free trial" from the internet or TV, contact your cc company. They can usually advise or assist you.