Poor service and feedback on damaged goods

I purchased 4 boxes of Nestle's Hot Chocolate sticks, from a hyper store in Pietermaritzburg, in September. Each box is meant to have 10 sticks. There were shortages in the boxes, with an average of 8 sticks per box. I have called Nestle's complaints line at least five times. Each time they have stated that they have my request on their system and they will send me vouchers but I still haven't received anything. It has been almost three months now since my first request. This is not acceptable.