sagging pool liner

Sagging liner. These two spots are the worst of them, but there are many others much smaller than this around the entire perimeter of the pool.

Hello, We're having a lot of trouble with getting our pool liner back in it's track. Two different pool repair companies have said that they cannot pull it back up to get in its track. They were simply trying to pull it back up into place (no boiling water and no water behind the liner). In...