Leak after Concreter poured concrete

Hello needing some advice.

I was about to build my Alfresco and needed a new slab and remove exisiting slab as its not standard. So they start to excavate and jackhammer the concrete.

Everything seemed fine until the concrete pouring began. Unexpectedly, there was a sudden leak in the stormwater pipe while they were levelling the concrete and didn't mention anything about leaks until I discovered myself when I got home. I am not a builder and have no experience at all. Unfortunately this is a bit stressful as I am unable to go to the next step of my Alfresco build.

Clearly, the builder presented various excuses and requested that I find a plumber to address the issue without damaging the concrete. After consulting with several plumbers, it became evident that the fault lay with the concrete.

What are my options? I still have the remaining payment.