Bought a garage door opener & it started making a ...

Bought a garage door opener & it started making a grinding noise immediately. The receipt says 30 day money back guarantee but after only a week the lady assistant manager refused to take it back & said we had to send it back to manufacturer even thought I had the receipt. Terrible service will go to Lowe's from now on. I should have read the reviews first because I see I'm not the only person they refuse to honor the 30 day money back guarantee for. Fraudulent advertising at it's worst.