OK, to help solve your problem. Try this. I use this Free WAV editing software in my studio. Its called WavePad. Just load your file and then resave it into whatever format/bit/sample rate you want. Supports sample rates from 6000 to 96000Hz, stereo or mono, 8, 16, 24 or 32 bits. I think it might get you where you want to be.
Yes it is completely free, but the free part has limited features, but includes the file conversion feature. Just pay attention when you download it so you don't download all this additional "trial" software. I think you get the full WavePad initailly then it defaults to the basic after a time period. Its a great simple free wav editor program
Good luck, let me know how you make out.
http://www.nch.com.au/wavepad/masters.html#101