If you already have an existing EPF account, you are not eligible to open an i-Saraan account because that account is meant for those who freelance without any official employment.
You can still self-contribute into your regular EPF account. Just go to any EPF kiosk to check your EPF account status. Once your account is opened, it should be with you for life.
Your regular EPF account will still work the same and would still continue providing you with dividends.

You can do it via online banking. It's convenient to just do a payment into your own EPF account.

I think Maybank is NOT the only option to do EPF self contribution thru online banking.
could you tell what bank do you want to use to do online banking to do EPF self contribution?
your info will provide the opportunity to forummers that had used that bank to do EPF self contribution to provides they responses.

Maybank, CIMB and Public Bank. Not sure about other banks.