Bogus bidders

[valentineval14]

I'm new to selling. 2 out of the 3 items I've listed don't feel right... 

ITEM A - sold in auction for £63, a price I was happy with. Successful bidder never paid, so I cancelled the order and relisted it. The same person won the bidding the second time, at an over-inflated price of £400. I knew she had no intention of paying, and I was proved right!

ITEM B - sold as 'buy it now' for a price I was hPpy with. Buyer paid but never responded to my messages in trying to arrange the collection. 
What's is going on here? Is this usual practice? 
Also, I wanted to contact a previous bidder to see if they would be I terested, but can find no way to contact them. 
Ive tried to report these people, but there are no 'categories' on the drop down lists that fit the bill of these strange (to say the least) people. 
Interested to hear your thoughts and advice 

Thank you

[arkwebus]

Certainly looks very odd.  This may be malicious by the first bidder.  You can perhaps contact customer service through "help and contact" [top of pages]  to see if they feel that it is and they might do something.  

As to the fish tank collection items often present a problem.  "Regret" "too big to collect"  "too far away" and so on.  Just go through the "cancel/non payer" method which will give you a fee credit and the non-buyer a defect. 

Two defects and he will not be able to buy!

@valentineval14