Question for eBay sellers about how shipping charges are displayed

Can anyone explain how/why a listing can show two different shipping charges? The seller I’m dealing with seems inexperienced or else dishonest (hoping for the former) and I want to understand what’s going on.

When I searched for a small appliance (filtered for US sellers only), several listings appeared with the shipping charge listed below each price. I clicked on one listing, and the shipping price displayed in the detailed listing was higher - vs $14.45 vs $9.55. I messaged the seller asking them to confirm the lower shipping charge, and they replied “shipping is $11”. I decided $11 was close enough and placed a bid but when the order was processed, I was charged $14.45 shipping. I asked the seller to fix it and they responded “Sorry, I already sent the package, but I didn’t check the shipping cost”. I responded that they needed to credit me for the difference.

My questions: 1. how did two different prices show up? 2. does eBay make it possible for the seller to issue a partial credit? If not, can I complain to eBay and ask for the credit? 3. Is it possible that the seller has shipped the item even though I haven’t received any tracking info?

I’ve been ordering from eBay more and more lately (hate giving money to Amazon), and have had great luck; not sure what’s up with this seller.