Samsung's promotional ****

I am very upset with the treatment I received from samsung after buying a washing machine from them for more than what I had budgeted for. The reason for my purchase was because Samsung had offered a R4000 voucher on any purchases with the promotion running until the 31st Dec 2018. I purchased by unit before that deadline and the requirement was to send an sms with the serial number. Now the issue is that my unit was only delivered late and I only sent the sms after the 31st Dec. Now the issue is that I've been told by Samsung through Dion Wired store in Woodmead that I do not qualify for the promotion anymore because I sent the sms late even after I explained that the delivery was late for me to unpack and send the sms. Now the question I have is that should we not buy promotions when it's closer to the closing date because there is no way I would have gotten the serial number because the specific unit was not the display unit but in a box somewhere in the warehouse. Are these promotions nothing but ****s? If I knew this was going to be the case, I wouldn't have spent R10500 on a washing machine, I would have spent less on different brand. May someone at Samsung explain to me why am I being treated in this manner. I pity myself because my TV is also samsung