Complaint Review: Frontline

We purchased Frontline Plus at our local Southern States, after a flea infestation of two of our dogs after we visited a friends house. We have several dogs and cats, and have maintained a flea/tick free environment for years.
We applied the product on Monday, by Wednesday, the fleas we still alive, well, and crawling all over those two dogs. We also applied Frontline Plus to all the other animals so there was no chance at a further infestation.
After a conversation with a Frontline representative, who assured me that the fleas would be dead between 4-18 hours after the application (THEY WERE NOT) I was informed that the "Satisfaction Guarantee" required three months worth of receipts to prove continuous use, and the return of any unused product, and they would replace and/or make a refund.
Who keeps receipts for three months, and who would imagine you would need prove of usage for three moth period? Nowhere on the box does it say that!
Needless to say Frontline plays a shell game so they don't have to take responsibility for their product when it doesn't work.