Did you try SOAPUI to test the webservice to check the result given? If the result in SOAPUI is correct then this is a mendix bug and you should file a bug report. Otherwise it is not going wrong on your side but is the supplying webservice at fault. Character coding can be tricky.
Regards,
Ronald [EDIT] Nice reading about character coding.
The result shown in the inititial question is result pasted from SOAPUI