R600 worth of Samsung voucher lost due to product return

I purchased from the online Samsung store using a R1000 Samsung voucher given to. My purchase was over R1000 so I had to put additional money towards the order. One of the items I ordered I had to return. I was partially refund in cash but R600 of the voucher was not refund in kind. This was in February, I call the Samsung contact center and they informed me it could take up to 3 months. It is now May, I call again and was informed that I mostly likely would not receive a R600 vocher refund and the value of the voucher is basically lost.

This is unacceptable, I do not need cash back just a voucher or online store credit. Fix this Samsung.