This is bad selling. The seller has selected that reason because it avoids a damaging defect for their account.
No one can force a seller to sell an item, but you can if you wish contact eBay Customer Services, explain the reason quoted for the cancellation is untrue , you did not authorise the cancellation, and you were disappointed not to receive your item. CS will review the case and may place that damaging defect on their account.
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 between 8 a.m. to 10 p.m. on weekdays.
9 a.m. to 6 p.m. on weekends.
I recommend contacting CS very first thing in the morning, when the lines first open, as there's more chance of Dublin answering.
@bella_2020
