Trying to list jewellery for sale and am getting that I need to add postage, but am having trouble doing so. Needs to be domestic post, with tracking and signature, I put in what I think I need and press continue but it keeps coming up with I need to add more, which I thought I already had. Put in the size of the bag which is 151mm by 229mm and they have it in cm. WHAT am I doing wrong. It is making me go crazy, there has to be a simple solution. Many thanks,
