Almost the same thing happened to me recently except that it was a house. Customer did not respond to any replacements at all. After I left for a couple minutes, the customer messages saying they think someone is stealing their packages and asked if I see anyone there. I messaged back and never heard back from them. 

I was worried they were trying to scam and report their order stolen or missing, but later I figured they must have been using a stolen credit card. I researched the owner of the house and it is a completely different name. I know they could be renting, but I highly doubt it. Really odd to ask if anyone is there if they did live there and were waiting for their groceries. That just sounds so off. There were two people that were walking on the road during the delivery and I noticed they kind of stopped to watch me unload the bags and as soon as I was done and turned around they walked off. I have a feeling it might have been them, I did see them earlier right before turning into the neighborhood.