Being it is a custom order, you ordered it through a Titleist account. Did you take the bag cover back to the account where you purchased it along with your receipt and let them handle it thru Titleist to see if they can repair the rain cover?

Limited One-Year Warranty Information
Although Titleist is committed to satisfying golfers with golf products of superior performance and quality, there is a chance a warranty claim may arise.

Acushnet Company warrants its Titleist products for a period of one year from the date of purchase against defects in materials or workmanship. Should your Titleist product fail to perform for either of the above reasons, we will at our option, repair it or replace it with an equivalent product at no charge. To obtain the benefits of this warranty, please contact your local golf shop to set up a Return Authorization. If you need assistance locating a shop in your area, please visit the Titleist Golf Shop Locator. Enclose the original receipt along with an explanation of the defect in writing. We ask that all parts of the product be returned to the repair department and that the product remain in original factory condition. Warranty claims presented without the original sales slip will be reviewed at our sole discretion. Acushnet Company reserves the right to inspect all warranty claims to determine the extent of warranty applications. All products returned for warranty claims become the property of Acushnet Company.

Acushnet Company will not be liable for any consequential or other damages arising from the use of this product or any delay in the performance of this warranty due to causes beyond the company’s control. Some states do not allow the exclusion or limitation of incidental or consequential damages, so the above exclusion may not apply to you. This warranty gives you specific legal rights, and you may also have other rights which vary from state to state.

I've always had good luck with Titleist bags.. this is probably my 4th or 5th bag. I'm probably not going to go through the hassle of sending the entire back back just because of the raincover snap. I'll wait and hope they send me a new raincover or just try to fix it myself..