H&M Recycling project misleading

Last week Sunday 22/11/2020,i went to H&M at mall Africa to donate our old clothes for their recycling project. I knew that 1 full refuse bag would give me 16 15% off vouchers. To my surprise the lady who assisted us gave me only 8 vouchers per refuse bag. I told her that I'm supposed to get 16 and she said no. I later checked other people who had taken clothes and they confirmed that they indeed got 16 vouchers per bag. I feel ****** because the reason I took the clothes was in hope that I will get enough vouchers to buy my children clothes for Christmas. Now I wish I had just sold them in the streets. H&M must understand that due to covid 19 some of us can't afford clothes for our children cause we lost our jobs and we really trusted that their initiative would help us still afford to dress our children well.