Unfortunately Titleist does not sell replacement parts. If you purchased the bag with the past year and have your original receipt, take it back to where you got it and they should be able to assist you. If you are outside the one year warranty period, can't help you much.

You might try Amazon. They sell replacement legs for golf bags in pairs. Generic off course.

During travel, I found one of my legs bent. I found replacements on eBay.