tub water leak behind diverter

[dianedebuda]

Used inspection camera to see fitting leak inside wall when diverter is in "shower" position. HVAC unit on other side of wall, so access not possible there. Looks like only way is to go in from tub side. Not sure what kind of tile is there; looks like random stone rectangles - not subway. Any way to avoid breaking tile to access for repair? I don't solder enough any more to feel proficient & make the repair in my son's house, so I've told him to get a plumber. Am looking for advice on his options. And cost guess? He bought the house this past summer. It's about 20 yrs old & was flipped.

And this tub doesn't have a flip-lever type drain stopper. Actually there's no stopper at all. Any idea what would be invoved to add this to the repair?

Thanks.