My seniors card has fallen apart can I get a replacement

Unsure where you live, but there is a replacement for a Seniors Card through the following web site if that is where you are:

https://www.service.nsw.gov.au/transaction/replace-lost-stolen-or-destroyed-nsw-seniors-card

https://www.service.nsw.gov.au/transaction/replace-lost-stolen-or-destroyed-nsw-seniors-card

FIXYA unpaid volunteers cannot issue cards.

Ask a trusted relative or trustworthy friend to help you get it replaced by whatever institution issues the seniors cards where you live.

Go to work force services, r a care Center for Seniors

"When applying for a Victorian Seniors Card you'll also receive a free Seniors myki"

Seniors Card https://www.ptv.vic.gov.au/tickets/fares/concession/seniors

No you have to apply to the state you live in.
NSW permanent residents aged 60 or over, who average no more than 20 hours' paid work a week across a 12-month period, can apply for a NSW Seniors Card. This free card gives you discounts and special offers at thousands of businesses across NSW. If you have a valid green Medicare Card you can apply for a NSW Seniors Card online.
If your card is lost, damaged or destroyed, you can Replace a NSW Seniors Card.

Hope this is what you are looking for:

Order a Gold Senior/Pensioner Opal card This Opal card is available if you are eligible and have a:

• Pensioner Concession card from any Australian state
• Seniors Card from any Australian state
• NSW War Widow/ers card

The Gold Senior/Pensioner Opal card is now available to interstate seniors and asylum seekers.
If you are a pensioner from any Australian state and territory or a NSW Senior go to the "Continue ordering an Opal card" button below to apply for the Gold Senior/Pensioner Opal card.
To confirm your eligibility, we will need to access the database of your card provider. In some cases this can take time. We recommend including your email or phone number with your application, so we can contact you when the outcome is confirmed.
Find out more about the Gold Senior/Pensioner Opal card