If the wrong size swimming pool liner was sent, then a Warranty will apply. Please read "How do I get a Pool Liner Warranty?" for all conditions and procedures of warrantying a pool liner. However, it is critical for you to first measure your pool one more time to make sure that the pool liner you ordered is the correct size, or the same as the pool size. This has happened hundreds of times where you get a pool liner warranty and receive a second pool liner only to find out that it also does not match the pool's size. For this reason (double trouble = pool nightmare), you should remeasure the pool again, to the inch, to make sure you ordered the right size. Do not go from previous pool receipts, or from assumptions, or from somebody's word....instead remeasure so you do not get into double trouble. For tips read "How do I measure my pool?" If you had the size right, then you can follow the guidelines on how to get a liner warranty.