Claiming back Import Duty/VAT on faulty goods

fly-catchers

I ordered a film scanner from B&H in the States just before Christmas. The price I paid them included the shipping and Import/VAT charges so the equipment arriving via DHL arrived within a few days.
It proved to be faulty and after arranging an RMA they arranged for DHL to pick up the scanner from me to return to B&H. As they couldn't repair it I took a refund. This was for the scanner but did not include the outward shipping or Duty/VAT costs.

Having downloaded the C285 form off the Goverment web site I am unsure how to proceed. They ask for EPU number whatever that is and Import Entry number amongst lots of other things!

B&H have told me to contact DHL which I am doing. But as they paid DHL directly I have no paperwork covering the importing of the scanner apart from an online receipt. And the later RMA letter together with the basic paperwork from DHL which I printed out when I sent it back.

As I am sure sending back faulty items and claiming the duty back cannot be that uncommon what else can I do?