You need to look at Section 85 and Section 86 of the strata Act. They allow for penalty interest of 10 per cent per annum on unpaid levies, plus the reasonable costs of recovery.
That means if you simply don’t pay the penalty interest, they can hire debt collectors to retrieve the unpaid amounts at your, probably considerable, expense. And the unpaid amounts will start accruing interest too.
As for the $4000, that may be the 10 percent interest broken down into three quarterly payments, but you would have to ask your strata manager how they reached this figure.
The owners corproation has considerable leeway in how they charge penalty interest, and how it is paid, so your best bet is is to talk to the committee and the strata manager as soon as possible.
If you simply don’t pay, you will not only accrue more interest, you will also lose your voting rights as an owner.