Ask them if the dog is OK, or if something is wrong with him. You've just noticed a ton of barking lately, and it's waking you up. When they say there's nothing wrong with the dog, you say "Thank goodness for that. Is there any way you could try to calm him down a little? He just keeps waking me up and it's really starting to kill me with work".
That way you sound concerned, non-accusatory and that might make them a little more sympathetic.
We have a million reasons for failure, but not one excuse...
Die Donks, DIE!!
"Oh well, there's always next year. We'll be better then, you'll see..." - Every Chiefs fan for the last 44...crap...45 years...