Design turned out well but the quality was very poor

I recently ordered customized stickers and a t-shirt for my brand. While I’m happy with how the design turned out, I was very disappointed with the quality of the t-shirt and stickers. T-shirts were extremely thin and see-through, white background on the sticker looked more like beige/off white instead of white which i didn't find suitable for professional use or for promoting my brand. Not a good experience so far