Hi spacecraft. The contact endpoint is still not working in the v3 API as far as I know. We’ve been waiting for some time to hear back from AC staff on this issue, but it seems radio silence. 
There are at least half a dozen other related posts asking about the same thing. Here’s a running list that I just put together:
- Contacts in V3
- Contact methods available in API V3?
- Version 3 API Road Map - adding a contact
- How to update a custom field, in contact, with API v3?
This list goes on, but I don’t feel like searching through all the forum posts to dig them all up.
And here’s a post that expresses that the contact delete API might not be working in v2 either: