Estate Sale Experts Charged me $20 late fee for a $3 pair of flip flops Livonia MI

I had been purchasing items from their auctions for a few months with no issues.  the last auction i did not see anything i liked so i bid on a pair of flip flops for $3.  during that time frame, my dog was diagnosed with metastatic lung cancer so I had forgotten about the flip flops.  i received an alert from my credit card saying something for $20 had been charged without the card present.  since i order often over the internet, i didn't think it was fraudulent but i wanted to check to see what it was for.  to my horror it was from the people who put on the estate sale. 

i received an email saying because i failed to pick up my item on time, i was being charged a fee to dispose of the item.  i responded to them explaining that my dog was very ill and i had totally forgotten about the flip flops and could they waive the $20 as a courtesy.  i emailed them a few times and never a response.  i understand the policy but i would think that even as a humane kindness effort, they would waive that fee.  how much extra work is it to keep track of a $3 pair of flip flops?  it's not like i just didn't show up, i am caring for my dog and the furthest thing from my mind was the flip flops.  they are absolutely cold hearted and obviously not animal lovers.  i warn anyone who thinks of participating in one of their auctions to beware that they are not nice people.