Try and put up a quick example of what they're asking for, to show how fast/flexibly you can do it with your current platform. At the end of the day how many projects massively over-run due to bad planning/estimations of development time, etc, etc. And how many project managers end up with their testicles (or other relevent bits, depending on gender) nailed to the senior exec's wall due to afore-mentioned projects abandonment, staff losses due to dissatisfaction, etc, etc, etc.