Man do I feel your pain.
That happened to us the second year after we bought the farm. It freaked me out how much water can get in and how quickly. Our basement is easily 1200sq ft, now fully furnished.
I ended up having a second sump put in as well as battery back-up in case of power loss, water alarms, etc. I also have stand-by generators and mobile pumps with the hoses already attached. I replace each pump every five years and keep the old ones as stand-byes.
Did I mention it freaked me out
Best of luck.