Complaint about sms Foschini voucher sent to me to be used in December 2019

I would like to complain about a promotion voucher sent to me to use over the 2019 Festive Season by the Foschini Group. The voucher could be used at any one of its TFG brand stores. The voucher was sent by sms and stated that I would get R150 off a purchase of R600 or more. That was the voucher's only terms and no other terms or provisions were stated in the sms received by me. I then attempted to use the voucher at @home living space at MENLYN Shopping Centre before Christmas. I wanted to purchase an item over R1000 which was on promotion. When I attempted to use the voucher at the till point when paying I was told that the voucher cannot be used in conjunction with the purchase of a promotion item. When I rep**** that this was not what the voucher stated I was informed that unfortunately I could not use the voucher for the purchase of the item. As a consequence of this I declined to proceed with the sale. As a further consequence Foschini lost the sale and I did not use and obtain the benefit of the voucher given to me. I feel that the terms of the voucher were not clear at all. Nothing was stated in the sms that the voucher has certain conditions that it is subject to when being used. Unfortunately the net effect of this is that Foschini lost the sale, I lost the benefit of the voucher and as a long standing loyal customer and account holder of the Foschini group one is left feeling disgruntled and with a sour taste in one's mouth! This is surely not how one treats one's loyal customers.