Here is something you might want to try. If you have a registered account with an on-line retailer and need to buy something, sign in to your account, put the item(*) in your shopping cart, and then sign out. I did this with GMpartsdirect.com, and the next day I received an email from them asking if I had a problem with their check out system, and providing me with a discount code to use in completing my order. The code was good for 5%. I tried the same thing with another site in the past week or so, and the result was the same. Again, I got an email within one or two days asking if I had a problem with the check out system, and providing a discount code worth 5%.
I'm sure this would not work with Amazon, but try it for other sites and see what happens. If it works, share the web sites with the forum.
So far, this worked for me at:
2001 Bonneville SSEi (retired at 365,000 Kms.)
2014 Jeep Grand Cherokee Overland (yes, I know its not a GM)