Hi there, thanks for your question.
To answer your first question about a printer rejecting a compatible cartridge...This happens because there is a chip on every toner and the printer reads the chip for up-to-date software. To prevent the use of compatibles, a printer manufacturer will often automatically update the printer software which means the chip on a compatible no longer matches the printer software and the compatible is rejected.
Unfortunately, manufacturers do this a lot, but there are ways around getting the printer to bypass the error messages if you prefer to buy compatibles. (you can read
how to do that here)
We offer a 3-year guarantee on all of our compatibles and 90% of the time they will work perfectly, but if you plan to keep some stocked up, when you come to use them you might have issues.
The top 3 products on the page are compatible toners and print 10,000 pages, 5000 pages and 3000 pages respectively. The last 3 products on the page are original Samsung and again print 10,000 pages, 5,000 pages and 3000 pages respectively.