Have to admit , it is difficult to understand your question, try to be more concise.
By the sounds of things , you have a pitched tile roof, with Fascia / Guttering on the sides ... right ???
There are leaks in the middle on both sides, builder states he cut Batons and reattached Fascia , but problem persists .... right ??
If right, I would tell builder you are not concerned about what problem is, but in a solution, he could be brought to small claims court, if unresponsive.
Looks like the tiling may allow water to trail onto batons (they should be covered by underfelt) ...... right ??, and coming down baton onto wall.
If priority is fixing, contact solicitor, and ask if you pay qualified roofer to fix problem, can you sue builder for costs