I also just heard of squirrels nibbling on flowers. Never knew they were fans of flowers (and am actually still skeptical). We fenced in a front yard so rabbits can't get in, but the day her tulips bloomed, a few had the heads eaten right off.
As for peteg's client - that might be the dumbest thing I've ever heard. I can't say for certain, but over the history of time, I'm pretty sure that not a single flower, planted correctly or not, has ever vanished from the end of a plant on it's own. Ever.
As for what to do next, I think the only thing you can do is shrug your shoulders and say "I'm sorry to hear about that." Even if you purchased the plants, and you offer a guarantee (which you shouldn't on petunias, anyway), having them die by hungry animal is the fault of the animal, not you.
One of the clauses in our
landscaping contract stipulates that if animals kill the plants, we won't replace them at our expense.
That being said, another of our policies is if we don't provide the plants, we offer no warranty on them. Seems only reasonable. Like bringing the car you just bought to Maaco for a paint job. Maaco won't warranty the car just because they put a coat of paint on it.
My $.02, anyway.