UH...OKAY. THANKS?

You could be a lot more grateful if you didn't know that the supposed gift/act was a part of a grand scheme borne out of guilt and/or a critical, demeaning spirit. Saying, "Thank you" would only make you complicit in the scheme, and confirm that you, too, feel better believing that you are inept, lacking, irresponsible, inattentive or incompetent. How do you respond when what others do isn't truly designed to help, or make things easier for everyone involved, but to add feathers to their own caps?
A self-centered individual's actions reek of control freakiness. Whether close up or from afar, their hands have to be in and over everything. Their intent is easy to discern. Some people don't think to ask, they just DO. They singularly decide what's best for others, thereby demonstrating not only a lack of respect, but a need to manipulate. God forbid that others have minds of their own. God forbid, someone else does something with excellence, let alone satisfactorily. A selfish individual strives to make sure the opportunity to demonstrate it never comes--especially in an arena they sincerely feel is theirs.
Their brand of generosity is flawed. Even when they're nowhere to be found, their giving still demands immediate credit, praise and attention. The kindness of their hearts is blanketed by their need to broadcast what they do, how much trouble it was to carry out in addition to everything else on their plates, and especially, how much it cost. There's always a catch involved in their sudden spirit of giving, as if what they do is supposed to scramble your opinion of their real motive. They need to make sure things are done to THEIR satisfaction, and according to their wishes, as if others simply aren't capable, have no preferences, can't, or won't devise a plan of their own.
Your response? Don't argue, complain, or try to make them see the grandeur of their selfishness. They won't. They can't. They're too busy reveling in the notion that they've done a great thing. Remember now, you TOO are supposed to be grateful for the fantastic, helpful thing they did in an effort to bring attention to themselves. Just nod and smile and proceed with YOUR plan. You need not pat them on the back, besides, there's no room for your hand. They've managed to get their own hand back there to do it themselves. Relax. Let them think they've saved the day--especially if it means less work for you, and proceed to enjoy your day--the way YOU planned.