Ok, so after many stops and starts I am at a situation where I have registered my own number which I can send the default test message to and I can reply and the webhook is working because I'm saving the payload at my server end so I can see it has come through.

However, when I try to respond to the message via the API I'm getting a permissions error. I tried to recreate the permanent admin System User access token and that comes up with the error "Unable to generate token Error performing query."

So I tried using the temporary access token, and that give me a permissions error too.

There's a payment source in place and the business is verified. What am I doing wrong now?