Advice on dealing with a faulty contracting job

We had our leaking stoop repaired about 18 months ago. The contractor replaced the slab and steps and supposedly installed a water barrier, repointed the brick, reframed and installed a new door. The job cost around $25k. When we finished the job and paid him in full, it seemed to be dry but since then we have had excessive leaks. He comes back and repoints parts of the brick or caulks a seam here or there, but it never works and we now have more leaks than before he did the job. To make matters worse, I had spent 4 weeks redoing the interior, hand painting a custom pattern on the walls and installing board and batten. The hand painted walls are ruined. Much of the cement board needs to be removed.
Does anyone have any advise on how to deal with this with the contractor? We cannot afford another $25K to redo this job. It seems every time we have work done on our house the reliable contractors don’t want the work because it’s not a full gut reno and too small a job. We did not and do not haggle with the contractors trying to get a lower priced deal. We are willi ng to pay a fair price, but we do expect the work to be done correctly. $25k is a lot of money for faulty work.