I have sagging fiberglass steps on an inground liner pool. I am getting a new liner and the pool company said they can drill holes in the steps and fill with "foam packs" that they say they want to charge $169 per pack for. I happened to be home when they sent a couple of teenage boys out to do this. By the time I was done mowing the lawn and went to say hi to them they had already drilled the holes and were spraying a $4 can of Great Stuff foam insulation into the holes. I am fairly certain that this will do nothing for supporting my steps. When I questioned the service manager he told me he would have to check into it and never responded. I asked the owner of the store and he said they use it to get the biggest voids filled so that they can save me $ when they put in the expensive packs. Am I out of line thinking that expandable foam was not what they were supposed to do and they are just trying to cover their tracks due to me catching them?