replaceAll takes a regular expression in the second parameter, so you can do this in one call.
replaceAll($Contact, '[\(\)\-]', '')
https://docs.mendix.com/refguide/string-function-calls#13-replaceall
Hope this helps.
try to put your code ekstra two \\ sings
$replaceAll($ReqBody,'\\*','')
Hope this works for you