The outstanding debt is $1,208
The debtor (brother) is paying $450 per fortnight.
Brother can pay this off in three fortnights, including interest. Here is my calculation.
Assume 10% pa interest added to it. I will add 3 fortnight’s worth of interest at 10% pa (but this is really an OVERestimation). With each payment of $450, the outstanding interest should REDUCE.
Interest for three fortnights = $1,208 * 0.10 / 365.25 * (3 * 14) = $13.89
Total required repayments over 3 fortnights
= debt + interest
= $1,208 + $13.89
= $1,221
If brother continues to pay $450 over the next two fortnights, he only has to pay $321 on the third fortnight:
$450 + $450 + $321 = $1,221
Ask you strata committee why they cannot wait six weeks for the entire debt to be repaid?
Even if, in six weeks’ time, another levy could have been invoiced, your brother has shown a willingness to get on top of it. A debt collection agency is unnecessary. I fear that your brother is being bullied.