N.B. Unfortunately due to eBay's new system of, "Simple Delivery", there is no longer an option that allows me to issue a combine postage invoice.
Regrettably postage labels are now generated by eBay for each transaction so consequently if multiple items are purchased and paid for within one transaction postage will be combined but if purchased at different times/days you will now be charged postage for each item and parcels will have to be sent separately.
Sorry, out of my hands but hopefully eBay will resolve this issue soon.