Incorrect credit to account

I returned 2 items from a order to North Beach collection point in the same box. I was not told to put it in separate boxes. One Item was credited R255 to my account but second item (R254) is still outstanding. So when will this be sorted as this is getting ridiculous? I want this matter to be escalated to senior management as I have not been given any proper answer as yet. I was told it would be sorted out but still no satifactory result. This is now more than a month. Complaints department is not very competent to deal with this issue since I have emailed several times.