hmmmm. That's a good question. Here's what I'd say."Why didn't you tell me that before you started. I would never have had it cleaned."
"Ma'am. I had no clue it had rubber backing until this occurred. This is probably the reason that rubber backing isn't a popular backing anymore. If you still disagree and are not satisfied, all I can offer is a refund".
Due to the age of the carpet, I still would not offer to file an insurance claim unless she pushed it with threats to sue