Pinnacle service

Asus issued me with an RMA number for return of my laptop on 6 December. The covering letter advised the collection would take place the day following issuance of the RMA number. A DHL barcoded shipping label was enclosed. Having called DHL regarding non-collection, they have requested a pick-up confirmation number. I have now spoken to a number of people at Pinnacle and no-one seems able to help me. Where do I go now ?