Your collection rate is a calendar problem
Committees describe arrears as a problem with members. Far more often it is three missing dates and an inconsistently applied rule, and neither requires a difficult conversation to fix.
Committees tend to describe their collection problem in terms of members: a handful of chronic defaulters, a general lack of civic sense, people who can afford it and simply do not pay.
Sometimes that is true. Much more often the problem is a calendar, and it is fixable without a single difficult conversation.
Three dates, and what they do
Consider the difference between two societies with identical members and identical charges. In the first, the bill goes out when the treasurer has a free weekend — sometimes the third, sometimes the eleventh. A reminder happens if somebody is annoyed enough to send one. A late fee is applied to the flats somebody noticed.
In the second, the bill goes out on the first, a reminder goes out on the eighth, and a late fee applies on the sixteenth. Every month. To everyone.
The second society will collect more, and not because its members are better people. It will collect more because payment has a schedule attached to it, and because nobody can reasonably claim they were singled out.
Uniformity is the part that does the work
Selective enforcement is the quiet killer of society collections. The moment a member can point at a neighbour who was not charged the same late fee, the charge stops being a rule and becomes a discretionary act — and discretionary acts get argued about, waived, and eventually abandoned.
This is also the legal position. A charge applied inconsistently is the one a member successfully contests, and once a committee has waived one it has effectively waived them all.
Take the awkwardness out of it
The other reason arrears run is interpersonal. A treasurer chasing a neighbour will see that person in the lift tomorrow and will need their vote at the next general body meeting. That is an unreasonable thing to ask of a volunteer, and the predictable outcome is that the easy cases get chased and the difficult ones do not.
A reminder sent on a published schedule by a system is not a personal act. That single change removes most of the friction, and it is the reason automation improves collection more than any amount of exhortation at an AGM.