Sellers do not have to combine postage. If you wanted that this should have been arranged and agreed before sale. Many sellers [myself included] would pack up stuff before an item sold so as to be able to despatch quickly.
I am not sure if you think that after buying with postage the seller changed to "free postage" [which should be impossible] but - as you have found - free postage = 5*
I foresee the day when all sales are post free
@nurse_vk
