how to open a bioderma atoderm 500 ml bottle

as the title said. i have a bioderma atoderm 500 ml in a pump bottle. there's some product left at the botoom of the bottle, good for about 2-3 washes but i can longer pump them out. i've tried to navigate the "straw" towards the leftover product but obviously because of the bottle design, the movement is limited and the product quickly flows back to the outer part. yes, it's only 2-3 uses left but in this economy i don't want to be wasteful. any of you have luck opening the pump by hand? i'm going to cut the bottle as a last resort. TIA