Assuming Simple Delivery was on your listings combining postage is not working at the moment. You can either cancel/refund the transactions with the buyer's agreement and relist with items on one listing and a single postage cost for the buyer to buy and pay again.
Or pack into one parcel and the cost of any postage labels that are not used will be refunded to whoever paid for them. If you do that the tracking for the other items won't be correct. You can contact ebay and ask them to change the tracking. Not sure if they're doing that now but it's worth asking. You can use callback on here:
https://www.ebay.co.uk/help/eua?id=5275&mkevt=1&mkpid
If they won't you will have to wait 14 days for the payment to be released.
