Any tpye of warranty from the installer on their work? Was it for sure the liner that failed on a seam or was there something wrong with the cove that caused the liner to split at the crease of the cove? Did the wall buckle from the water leak/spill or from frost heave?

You have my sympathy - its a mess. I sure hope things turn out the best for you and you can get back to your backyard paradise very soon.