No, you can manipulate the total VAT using several lines on the purchase invoice. e.g.
Line 1 103.45 plus 20% VAT
Line 2 -103.45 plus 0% VAT
Grand total is £0.00 plus £20.69 VAT, i.e. a VAT only invoice.
Then you just add the advancement fees, although DHL would never reply to my emails or queries about what they were actually charging me as their “VAT invoice” was severely lacking in detail, so I never pay and they never follow it up.