How to create a Mock server for SMEV 3 services?

Question

Software testing

There is a problem:
There is a GIS SMEV 3. It has types of information (services) through which the state interacts. institutions, ministries, etc. Example: The Ministry requests data on a counterparty from the Federal Tax Service via a SOAP request, the response receives data on this counterparty.
SMEV3 provides a test service for testing, but requires sending reference requests there and giving reference answers, which does not always allow bugs to be caught before production.

Has anyone encountered a similar problem and how did you solve it? It comes to my mind to use some SoapUI, but I almost don’t know the program. Share your experience with SMEV 3, thank you!