It is clearly feedback black mail, which TM look at in a poor light. From the TM feedback policy "As outlined in our code of conduct, members should not replace retaliatory feedback. " It maybe best not to mention this to them as otherwise they may manuipulate the wording of the negative to make it look as though its not retaliatory. But if they go ahread with it, you can do a feedback dispute with TM and you have the email to show TM that it is retalatory.

Im on standard as Callum, no VPN, but have ad blockers

I also have exactly the same issue as alan with firefox . I also find I cannot contact TM on firfox through the chat bubble, so go over to chrome for these activities. If I was soly on fire fox there would be no possible way to contact TM, as it both blocks chat bubble and all the other messaging to TM

Absolutley, as L says. However reporting them to TM maybe a waste of time as if it was a genuine mistake, by not completing trade at the original price, they are following the law of the contractual mistakes act, and TM authority is not above the law. But it maybe good for TM records if this was an on going recurring situation

Legally, if that was a genuine mistake, yes they can do that under the contractual mistakes act. Of course "genuine mistake" is the important words and then the hard bit is to prove in is genuine or not. it would however be looked at in pretty bad tate though.

Yes, its king of annoying. While all my courier stuff has TM shipping templates attached to them, I have some larger item which have to go on freight. My freight company quotes per job location( and dont produce a set of rates) so its not possible to quote as per TM shipping templates as there are many hundreds of different prices for NZ. King of between a rock and a hard spot. While I offer shipping options to main cities , business zone delivery, all other locations need to be custom quoted

No Amy. There is no rule about "when" you should place feedback as it is voluntary , you can place when you like or not at all. TM do however have guidlines about feedback. " General guidelines All Traders are expected to maintain a feedback rating of at least 95%. We encourage members to place feedback for all trades. Feedback is a permanent part of your Trade Me account. Negative feedback can be disputed for up to 45 days from the date of purchase.   Although certain exceptional circumstances will result in feedback being removed or edited, feedback will remain a permanent part of you...

If possible split into multiple less voluminous parcels as couriers will then be able to take probably

If within same city, $8.50 would pretty much cover a stamp album. Can only see the reason for asking extra shipping if you paid urban shipping but are a rural address "with his courier", then $6.50 is ok for the rural extra price

It seems you have already identified what "may" be the issue, ie thet they have more than one of that item to sell. If they only had one and they put it out for bidding, and it did not reach the $$s  they had hoped for, they may be tempted (against TM rules) to relist at a higher price and abandon your sale. If they are selling it at the same price as you bought for, there is no benifit in them relisting, if only one item.