I ordered a microwave part from Certified Parts, which arrived two weeks later. Fortunately, it was the correct part. According to their website, Certified Parts offers a "Hassle-Free Returns" policy. I tried to return the part within their 30-day window—unused and still in its original packaging.
Over a two-week period, I made multiple attempts to use their online Returns link, but the system never recognized my order number and zip code. I also emailed their customer support three times but received no response or assistance in processing the return.
Many other vendors provide far better customer service. While I can’t say for certain, I suspect Certified Parts doesn’t keep inventory on hand—instead, they likely order parts from another supplier and then ship them to the customer. If that’s the case, returns would create a storage or inventory issue for them, which might explain their lack of responsiveness.