Starts off automated, but you can opt to speak to a real person.
Accounts department regarding payment

I returned a call from (03) 8375 9131 but reached vm for Linkt

linkt legit call

I received an email 1.5 hours ago about "Hurry, this is you final payment reminder" and we may "refer to a debt collecting agent" from Linkt (formerly called CityLink) so it's likely that it was them now calling as well, but they didn't actually say anything at all, it was just quiet.
More annoyingly:
A. the previous message from them a week or so ago didn't say anything about a time limit to pay any outstanding amount, just that they had suspended the account because of low funds and if you travel before you pay up you may be billed which is more expensive than pre-pay account
B. The "outstanding amount" turns out to be $15 which doesn't seem to warrant the threatening language
C. I paid this, 1.5 hours ago - surely their system should see that it's been paid, as it was an online payment
Rubbish!!

I called back number (03) 8375 9131 reached IVR for a company called Citilink.

Yes, I got the same call, I think it is a scam

Citylink - Legit

CITYLINK MELBOURNE:- Automated message with a computer voice reminding you to pay your account (legitimate call).

I called back number (03) 8375 9131 spoke to a woman who said company name is citylink toll road.