Ok so some actual info time.
Here is a link to the Police's speed enforcement guide. Note how they are GUIDELINES only, not hard and fast rules.
If the demerits are truly going to screw you over, how much longer do you have to wait until your oldest ones expire? Because the demerit points only accrue onto your licence when you pay the fine, you can stretch this out over a while if neccessary. Here's how:
1. Police will mail you an infringement notice. You have '28 days' to respond.
2. 28 days expire, police will send you a 'reminder notice' with another '28 days' to respond.
3. On the 27th day of the reminder notice, send them a letter explaining the circumstances in an attempt to try to get them to drop it. They probably won't, but as long as you've chucked said letter in the mail before the 28th day, you have extended the time some more. Plus you've made them work for your money, yay.
4. They'll send you back a 'no, stuff off." letter most likely, but this will take around a week, during which time you still don't have to pay the fine. With said letter will come another reminder notice, with another 10-20 days to pay attached.
5. At this point you can either:
5a. Pay the fine on the last day and the demerits will be accrued onto your licence at that point. If you don't pay the fine after this they can impound your car etc so yeah
or 5b. The day before your time runs out, send them a letter requesting a hearing in respect of said offence. They legally have to give you one, and you gain more time while that is organised and carried out.
So yeah. You can stretch it out by like 3-5 months if needed...the worst that can happen is that you lose in court and have to pay another $30 on top of the fine or whatever. The best that can happen is you get off scot free.
THIS IS NOT A REPLACEMENT FOR ADVICE FROM A LAWYER. ;D