Thank and apologize for what the other party did but failed to do

If you ask for help from others, the other party has tried his best, but due to the restrictions of various conditions, the thing has not been done, and he has paid hard work for it; or if the thing has been done, but the other party has encountered unimaginable trouble. Why can't you express your heartfelt thanks and apologies at this time? This shows respect for other people's labor, and it's better to speak again when you ask for help.