Lower audio sample rate in an mkv?

I have some mkv files in which the audio plays too fast, so i'd like to change the sample rate to 44.1 from 48k so it will play the audio slightly slower. The audio currently is playing at a faster pitch, literally sped up, eventually playing ahead of the video if played for long enough. So i'd rather have it slow it down also changing the pitch. Does anyone know of some software for windows that will just remux it or whatever to have the file play the audio slower? I don't need a "player" that will play it slower, I need the file itself to be changed.

I hope this makes sense. I barely know what the hell i'm talking about. ;)

Thanks!