2018 Buick Avenir wet front floor

The front floor of my Avenir keeps getting wet to the point I had to replace the carpet underpad due to mold. The first place I took it to checked the a/c and said it was fine. They wanted a crazy amount to blow out the sunroof drains, so we did it ourselves. Still leaking. Took it to the dealership’s “leak specialist”. They said the sunroof drain was broken & the underpad needed to be replaced. $900 later and we still have a wet floor. Took it to a third place yesterday. They blew the a/c out twice (nothing came out). Does anyone have any idea of what the problem is? Thank you