The contact details of APFC,RPFC,Addl CPFC,CPFC i.e. address,phone number, email id,are given in the EPFO directory at:
RTI shall be better option.You may write that for reply by redg/speed post ,the postage prepaid( as purchased from PO) self addressed envelope is enclosed.
You can contact PRO also and the staff is duty bound to reply with details.
You can also lodge greivance at;
the web link is: