We need help along similar lines. We are trying to provision using web services connector and whenever the values contain a special character it’s just dumping junk characters on the target. Please see the post link below.
In our case, we see in the log that the HTTP payload does have the special characters but after the call is made when a response is returned it comes back as junk character. You do the same operation via postman and it works just fine, that tells me there’s no API limitations from the target system side