Test one thing at a time. It feels slower and it is the only way to learn anything. Same for me with TB-500, unfortunately.

Photograph everything before you open it. Ten seconds, settles most disputes. Currently on a redelivery myself.

Written confirmation email after every phone call. Cheapest insurance there is.

You are not imagining it and you are not being difficult. Document it and take the document in.

Log dose, time and sleep. Ten seconds a day and it turns the anecdote into something you can look at.

Worth asking what specifically was measured. Pain scores move with mood and function does not.