In this line within your wvdial.conf file:
Modem = /dev/ttyUSB0
This does not appear to be consistent with what the output of wvdial is informing you of, which is:
--> cannot open /dev/ttySUSB0: no such file or directory
I would suggest ensuring that the line within your wvdial.conf file matches what the wvdial program is looking for first. Or, you can create a symbolic link to this /dev/ttySUSB0 and see if this has an effect.