Please visit the site of ECHS for any specific Query - https://echs.sourceinfosys.com/
All contat details for ECHS in and around Mumbai are available on the link below.
https://echs.gov.in/img/contact/mum.html
Now in case of an emergency you can avail the CASH payment facility at HORIZON PRIME HOSPITAL
The hospital has agreed to charge according to CGHS rates to all ECHS Holders. That means , you can claim the entire amount back from ECHS if the case is an emergency.
Otherwise also if you produce your ECHS cards, you can avail all OPD services at CGHS Rates which are very reasonable.