I propose a call to arms on this! You can make this go away! Here's how:
So, this just happened to me with almost 2 hours-worth of shopping in my $700 basket. This included a lot of custom paint as well. I ended up standing in line for like 30 minutes trying to get someone to override or a human contact at Certegy. Of course, nothing happened and in the end, we just left them with our purchases and went out to eat.
It occurred to me later that my visit probably cost Home Depot quite a bit of money. No, I don't mean the money that I -would- have spent there but wasn't able to because they wouldn't take my check, that's lost of course, but they never had that. What I'm talking about the real cost that the entire episode caused them. Things like their overall customer experience (I had a register line tied up for 30 minutes trying to call Certegy and eventually someone had to come up from the back to open a register to handle the large backlog of waiting people), the employee -time- it cost them (I had like 2 supervisors and the register employee tied up for at least 30 mins, plus the guy that had to open a new register, -plus- the time it took employees to return all my -wide- variety of items to the shelves later), plus some of the materials themselves were actually custom, one-off things (custom cut lumber, mixed up paint colors, etc.) that they had to hope to sell to someone else at a discount or just eat the cost of.
My plan is this: do this every freaking day from here until they take my check. Every few days, I'm going to go back and attempt to buy the exact same things (and more, -every freaking thing- on my building materials list this time) with this check. It will only take me a few minutes each afternoon to assemble all my custom supplies (including all my custom colors for my entire house, custom lumber for my projects, etc.), then leisurely stroll up the register with my $500 in custom paint and multiple baskets of odds-n-ends. Then, I'll back up a line, call in some managers, and let them eat that cost every single day I go in. After a couple weeks, I should be costing them tens of thousands of dollars. What can they do? Kick me out of the store for attempting to buy something with a -perfectly valid check-?
Here's where you come in.
I encourage every one reading this to do the same. If you found this site like I did (from just trying to buy something and getting 'Certegy denied' for no reason), I encourage you to run right back there in a couple of days and do it all over again (and again and again and again). I might not be able to make a difference nationally (though I plan on putting the hammer down on my local store), but if all of us just did it a few times, Home Depot would quickly have to start rethinking it's policies on using Certegy. It wouldn't take long before they'll have to start explaining to stock holders why they are loosing so much money.
It costs nothing to contribute! Do this same thing any place where Certegy denies you a purchase with no good reason.