For the parcels with no updates, just assume they have been delivered - unless you hear from the buyers, they probably have.
You don't need to do anything about the first one. When you get the item safely back, refund the buyer and relist the item.
You can try contacting Royal Mail to complain about the tracking not updating on the parcels that appear not to have moved.
"There are two ways to be fooled. One is to believe what isn't true; the other is to refuse to believe what is true.”
Søren Kierkegaard, Danish philosopher (1813 - 1855)