I bought something from a private seller last week, and it arrived today. The seller charged £8 postage, and I tend to look to see what the actual postage charges are, partly because I think it's not fair to overcharge here.
In fact, the seller had clearly put in into the post system at their work, it was clearly marked with the logo of where it had come from (NHS!!!). So, they had not paid anything for postage, it was quite a light package.
Would anyone contact the seller about ths?