no, wait for th epost to deliver it.if it s registered, it will more than likely get thru. if it doesn t, then you have a claim and you can refund him once it is clear this is what happpend, which will be clear when the post refunds you...as for now, it hasn t been 15 business days, not by a long shot.however, in good conscience to your buyer, i would communicate all along the way and even include the tracking info so they can verify what you say.
Talk to the buyer, explaining the item may be delayed due to recent industrial action.Sometimes parcels do take a long time to arrive - they should have had it by now though. Explain to the buyer and if it never turns up you will go into dispute. Ebay has a good procedure for this and as you sent it recorded, you can prove Royal Mail is to blame. Ultimately, the buyer will have to contact Royal Mail- but try to help as much as possible!