I can understand how angry you'd feel at an unjustified slur like that. I'd be livid too.

Ebay will never explain why but my bet is it is because you have won an awful lot of auctions from the same seller. I don't know how many, but dozens, if not into the hundreds.

It's obvious to me, a mere human, that you're buying because that seller happens to stock the sort of items you like and you're a collector. And unfortunately, that seller is using an auction format for almost everything. You wouldn't be having this problem with buy it now items.

The ebay system may throw up some sort of red flag when it notices a high % of bidding on items from the same seller. Mind you, you'd be a pretty poor shiller (is there such a word?) if you were accidentally winning all these auctions. The whole point of shill bidding is to get other bidders to increase their bids.

How do you normally bid? If you bid in small increments & rebid manually once you have been outbid, that might be a red flag to ebay too. It would be better to make your highest offer first, then sit back.

I am not sure if any of the items you have bought from that seller had tracking. I tend to think not.  If several have though, you could contact ebay via chat (not email) and ask them to look and point out that if you were in cahoots with a seller, you'd hardly be likely to actually be paying for registered post.

I know that the seller mentions preferring direct deposit, but if this is how you pay, in future pay only by paypal as that will leave a tangible record and proof of payment.