What was wrong with them? The 150 side is for lapping stones, not sharpening. U should contact the seller, if u mean the DMD prism sharpener with stand below. Then leave an Amazon review to help others.

DMD Diamond Whetstone Knife Sharpener | 3 Sides Grit 150 325 1200 https://smile.amazon.com/DMD-Diamond-Whetstone-Sharpener-Special/dp/B099SDTBNF

...60-DAYS hassle-free 100% REFUND GUARANTEE and Lifetime diamond wear out WARRANTY. If the diamond wears out any time by simply getting in touch with us and we will refund you 100% without hesitate!