Sandbox / Staging env

If we’re a paying customer I feel like a sandbox / staging env is a must. If not at least offer a test account to be at the same level as the paid one for testing.

How can we co-mingle production and test user data otherwise, just not ideal!

Using a free account is an option, but then we run into bugs/restrictions (API/modules) etc. which make testing hard and then cause issues to pop up in production which we were not able to test first locally or on test envs!