However, Netflix ships millions of DVDs each day to millions of people. It is inevitable that some of them will be worn out. The "life-expectancy" of a typical rental DVD is only about 20 rentals, and then it must be replaced.
I'm assuming you're using their Web site to report damaged DVDs every time it happens. They will send you a replacement DVD right away. However, calling customer service about damaged DVDs won't do any good. The best and fastest way for them to find out a DVD is worn out is when customers tell them through their Web site. They've fixed it so that you can report a damaged DVD even after you've returned it and Netflix has received it. Their sophisticated tracking system will alert them the next time they have the disc, so they can either repair or replace it.
To report a damaged disc, go to your account, to the Rental Activity section, and click on Report Problem.
From the Netflix Help site:
"Q: I received a scratched, damaged, or unplayable DVD. What do I do?
A: If you have received a DVD title that is unplayable, try cleaning the disc first. (window cleaner on a paper towel works well.) If the disc is cracked, damaged, or still won't play, you can report it at the Rental Activity page in Your Account.
Please return the damaged disc, as many damaged discs can be repaired with our polishing machine. Also, for many titles, Netflix must account for, or pay the movie studio for lost discs; your return of the damaged disc is appreciated, and helps keep costs low for all our customers."