There’s something inevitable about the next bit (the seller woefully underquoted P&P although said a 3-5day economy Courier would be used in the ad.)
” Hi, went to post your item today and as the [xxx] is nearly 3kg the postage would be £12.98. I really didn’t realise it would be so much as went along with ebay’s suggested postage charge. If you could let me know if you are willing to pay the [ greater than £8] difference or if you want a refund. Thanks very much regards [xxyyzz]”
Told the seller as they’d sold about 100 items based on their seller feedback they should know the ropes & not hide behind Ebay nonsense. And that they could send it by Collect+ or Hermes :-< to save money as I don’t want an unadvertised service upgrade to Royal Mail at my expense. I would have bid a lot less.