You would have to find out the manufacturer, then call them.
Gardenwinds.com
www.costlesstarps.com
A seat replacement for a canopy swing can be purchased with the manufacturer in most instances. If the canopy swing is still under warranty, the replacement may be covered by the company.
Try searching the internet for the brand name and model number. You could also try contacting Costco and see if they can help you. Better yet, contact swingcushioncovers.com. They make the replacement canopies and cushion covers for all makes of outdoor patio swings using Sunbrella fabric, so it won't fall apart after a few years. They specialize in the Costco patio swing.
The canopy is probably unique to the brand of patio swing that you purchased. Check out the website for the brand. Otherwise, you may be able to use the old one as a pattern and make a new one from that.
s
To purchase replacement connectors for the canopy on a patio swing you can first contact the company who manufactured the swing. Secondly you can return to the store it was purchased and look for replacement connectors.
You should check your big box stores such as Lowes, Menards, and Home Depot. Amazon also sells them.
wallmart.com
There is a website that makes replacement swing cushions and canopies for patio swings sold at Costco, Wal-Mart, Target, Lowes, Sears, Home Depot, Wal-Mart, and other retailers. See links. They're made with Sunbrella fabric so they will last for many many years (Sunbrella awning fabric comes with a 10 year warranty). They have a good selection of fabrics. They seem to have a very large selection and cover just about every model.
You can buy a replacement canopy for your patio umbrella online. It will cost you about $40 and includes everything you need to put up the canopy with success.
Craigslist