CW, I feel your pain. Really I do. In my time, I've heard enough of such horror stories to fill a book.
Not all tradesmen are wonderful, or even helpful. In a perfect world, anyone, not only tradesmen, but anyone who treats their trade and their customers like this would be barred from trading at all.
In my experience, the smaller the problem (a leaking overflow for heaven's sake), the more they show themselves in their true light.
Rant over. Down to practicalities.
The “job” is the most important consideration here. After all, I'm sure you know you have a legal duty to your tenant.
He is never going to put this right. In fact, you really do not want him anywhere near it.
You have a “friendly” plumber willing to make the repair at a sensible cost. Let him do it.
If you pursue this, you shall invite nothing but frustration and stress upon yourself. Believe me, even if this prat returns, it will not be fixed. It will be patched only enough to placate you. Then, you shall be calling on your own plumber after all.
Walk away from this conflict. It has already ended in tears. The bigger man is one who's willing to make a small sacrifice for the sake of the tenant, and... your own sanity.