How to identify the plumber or electrician with proper certification? 

and any regulation/standards on the service price?

feel that nowadays everyone can be plumber and electrician to provide such service, and simply charge without proper quotation.  

http://www.saj.com.my/V2/Plumber.php

If need certified plumbers to install water meter in Johor. There is this list. 

how about the repair and installation within premise? 

@6011_3531_5354 thanks for sharing