Total ******* and no consistency

I recently opened an account and I was given R600 worth of vouchers, I made a purchase but had to return it and made an exchange with a different item but I was told that I forfeit my vouchers.

Why would they say it is a voucher if you can't exchange if the item you bought is not comfortable? I would understand if I was not making another purchase but it was an exchange.

This is a total *******, maybe if I was informed the day I used the voucher that I would forfeit if I return the item then it would have been perfectly fine by me.

There is no consistency because I used my R100 voucher to buy something else but there was no problem when I returned the item for exchange.