the sooner you report it, the better, usually within 15 days.

regarding the sampling inspection, under normal circumstances, the sampling inspection order is to buy two pieces at a time, one for the first sampling inspection and one for the re-inspection. If the merchant expresses doubts about the quality inspection result and applies for re-inspection, it is not necessary for the merchant to re-send the sample, but the inspection agency can conduct a re-inspection on the other piece purchased together at that time.

Therefore, as long as the sampling inspection is unqualified, there is basically no chance of passing if you apply for re-inspection or appeal. Finally, I suggest you do a good job in quality control and reduce the number of quality refunds, which can effectively reduce the chance of being sampled.