Apparently there has been a change from Dunnes in relation to the way or entitlement to money off vouchers
The €3 off €15 and the €5 off €25 are what Dunnes calls "Threshold" vouchers which are a one time use
You may or may not get a voucher back when you use one
But if you did a €15 or €25 shop without a voucher you probably will get get a voucher for your next shop
The €10 off €50 is a "Topup" voucher and you get one back when you use one
if you spend more than €85 using one €10 off €50 there is a high chance you'll get two €10 off €50 vouchers
So now we have to organise our shopping in multiples €50