Awkward membership cancellation

Cancelling a membership in CR can be very awkward and irksome. We've experienced multiple instances of a member's credit card being charged when their membership was set to cancel. This is a key piece of functionality that could be and should be addressed in a much better way. For example, CR should provide a membership cancel option that does not depend on guessing or determining the "right" cancellation date--it simply assures that membership doesn't renew, period. In addition, allow for a "Cancel after this date" kind of option...but make the simplest case ("Do not renew") easy to accomplish e.g. a simple "Do not renew" toggle that removes all date dependencies.