Was mucking around with entering promo codes on the Z app and to my surprise 'Test' and 'Test1' worked and both gave 1x free hot drink voucher.
I don't know how long it'll remain valid and probably wasn't intended to work.
The vouchers appeared instantly (after refreshing the voucher area)
Expiry dates of vouchers are 90 days.
Need to download 'Z' app on your relevant app store.
Americano, cappuccino, latte, mochaccino, hot chocolate, espresso, long black, chai latte, lemon ginger & honey, tea, fluffy. Add any flavour shots at no extra cost.
For more codes (10c off fuel and hot drinks) see the new post by Wakrak