Pre-Sales Customer Success to Tech Handoff

Hi everyone, we have started helping enterprises in Indonesia with Feedback solutions with our CX product. And our current state of customer success starts from pre-sales till upselling. 

As we provide custom solutions it involves a lot of tech communications between clients and CS team. However we are facing a consistent problems of clients asking for more customizations as a Scope is not defined.

Has anyone in the community gone through this process at a SAAS startup and uses any format for Scope of Work and getting it finalized even before the tech team involvement.

If yes could you please share a sample doc or process followed.

Thanks a lot