Bad service

I have received a pair of shoes as gift, so when I went to change the size I was told to pay in R90.00 as the special finished the previous day, I have argued this as I wanted to know why must I pay in the difference as this discount was supposed to be dealt with internally, I have reported this on the 06/04/2021 and was told that it was going to be escalated and I will get feedback in 48 hours and today is the 9th and I didn't get any response. I called and was told that they were busy with other complaints and that they will call me as soon as they have reached a verdict. I am so disappointed with TRUWORTHS