Toner has despite the high level error

it was promised that the toner can print many, many pages and a workaround was even resolved, with the help of which one was able to revise erroneous reading of the levels on the part of the printer. Short: It seemed to me also the supplier reputable and friendly.

Until now everything perfectly with the toner (~ 800 pages printed) worked, but since this morning there on each printed page ugly fragments or other stains. As long as I like printouts things just for me and my studies not be particularly bad, but just when it comes to formal letters etc. pp. goes is actually almost full toner for me now unusable. Recalibration remove and reinstall, turn off the printer and switch it brought no improvement, so I can only assume that the problem of the toner itself.

From my side so the clear recommendation to buy another product.