It's not a case of fraud, it's a case of bad selling.
The seller has selected the reason ... buyer has requested to cancel, because this does not give them any defect on their account, it doesn't affect their seller performance status.
No one can make a seller send out a paid for item, but you can if you wish, contact Customer Service, explain you did not authorise this cancellation and were very disappointed not to receive your item. You will not know any action CS will take, but they may well place that damaging defect on the seller's account. It doesn't take many to remove a seller from eBay, as they do not like unhappy buyers!
You can leave appropriate feedback but don't mention any case, refund or eBay involvement, something like..... Very disappointed seller did not complete this transaction, will suffice.
If you need to, this is the easiest and quickest way to contact eBay Customer Services, for a Call Back option.
https://www.ebay.co.uk/help/eua?id=5275&mkevt=1&mkpid
Lines open 8 a.m. - 10 p.m. on weekdays
9 a.m. - 6 p.m. on weekends.
Automated agents will be available on chat outside of the above hours.
I recommend contacting CS first thing in the morning as there's more chance of Dublin answering.
@harvey8175