eBay are not interested in reviewing account defects for regular sellers. It requires manual work, which costs eBay money, at no obvious benefit to eBay. I would imagine that the reviews are often automatically rejected.
If you sold items, posted next day and they were delivered after 2 further days then that's 3 days total. eBay likes to use your previous selling experience / tracking numbers to calculate Estimated Delivery Dates, so if you've previously had items arriving in 2 days then eBay may make that assumption for current/future sales. If you dispatched on time, used the service you stated on your listing and that was delivered on time (e.g. 1 day for 1st Class/Tracked 24 or 2 days for 2nd/T48) then you did your job, it's eBay being overly optimistic, there is nothing you can do. Best to ignore things outside of your control.
Stolen items: it isn't your fault, but I don't think a seller should be able to say to eBay "they were stolen" and get all defects removed, otherwise unscrupulous sellers would use that excuse all the time. For that appeal to have grounds I think the seller would need to provide a police report, but eBay aren't going to be interested to collect evidence and review it. It was a one-off event, bad luck presumably, you continue doing your job and your defect rate will go down again quickly.
