That's half the reason I just put the bag itself into a bin when it's time for a new one. That way if somethings wrong, it's mostly contained and I only need to take out a small amount to get the bag back out by myself.Now for sure they should not have had a rancid bag of feed on the shelf to begin with. That was their problem for not investigating the smell, storing correctly, or checking LOT numbers. However, if they said that they would refund without you bringing the bag back, that is technically good customer service at that point.
Speaking as someone who works in a feed store, if a customer complains of mold in a product we usually need the bag or the product back if it was taken out of the bag and the bag tossed. Our suppliers need the LOT number to track if there is a widespread problem with that batch, and our store policy is that the product must be returned for a refund so we can ensure it's properly disposed of. Otherwise a customer can complain of mold and then keep feeding the bad product, or just outright lie in order to get a refund. It has happened before. At no point would we ever drive out to a customer's property and retrieve a bag from them. That opens us up to liability if something happened to the employee on the drive, or if something happened on the customer's property, etc. Most stores do not have a company vehicle either, so it would be an employee's private vehicle that is not insured for business purposes going to retrieve the bag, which is another huge can of worms in terms of what does the employee get compensated for driving, etc.
That being said.
Before you dump any bag of feed into any container, you need to check it to make sure it is what you were supposed to have been feeding and that it is fresh, good food. I have had so many customers grab a bag because it looks like the one they usually buy and ignore what the bag actually says only to figure it out weeks later. And I have also had many, many customers buy a bunch of bags and just randomly dump into a bin without rotating, cleaning, or making sure that the feed did not get spoiled while sitting on their barn floor and then try to say it was the store's problem they had mold. Mistakes happen.
I have also had bags that have excellent dating, smell fresh, look great, and have had random chunks of concrete, mold, or other bits in the bag that was only discovered after scooping out a little bit of feed. Every bag that you buy should be checked before you put it into your storage containers/facilities regardless of who you buy it from. Mistakes happen.
For the rest of your experience I can make no comment. All of that said, I'm sorry, it sounds like you had a very rough and frustrating week.
TLDR: not needing the bag back to refund money was nice, them not coming to get rid of your moldy feed is smart for legal reasons, and please, please always check your feed before you store/feed it; sorry it sounds like a bad week hope it gets much better.