Hi. I can't really provide an academic framework, but the way I see it is basically that even though you've provided the person with an honest explanation and even an apology, they're still a bit angry - for their own reason really, it's in their mind - and so the taint of anger is still speaking when they essentially dismiss your explanation and apology as an 'excuse'. I think, in their own way, what they're really saying is 'try harder, please, or I might have angry feelings again.'