It sounds as though the wall switch feeds the pull switch, so takes priority. When the wall switch is off, the pull switch is dead. When the wall switch is on, the pull switch is in control. It sounds as though neither switch will take two-way wiring so both would have to be replaced, and wired up differently, probably including extra cable between the two.
Look at it as a switched table lamp plugged into a wall switched socket - if you turn it off at the lamp, the wall socket is already on so you can't put the table lamp on from there.