Please forgive my generalizing, but there aren't a lot of specifics to work with. Scope creep is often a major factor in situations like this. In my experience

Please forgive my generalizing, but there aren't a lot of specifics to work with. Scope creep is often a major factor in situations like this. In my experience product people usually believe that relatively small feature changes imply relatively small engineering effort, and of course that doesn't hold generally. Sometimes product people will try to sneak scope creep by as a "clarification" of requirements, which almost always leads to the situation you're in. So, depending on your environment, it may be constructive to draw attention to this, if it's applicable.