I felt like I was in an episode of Utopia on the ABC, however, we at least had a contact.

Here is the official response

VicRoads Enquiry Reference 501748517

Thank you for getting in contact with your concerns for Nepean Highway, Mount Martha between Craigie Road and Forest Drive. Which has been allocated reference number 501748517. I apologise for the delay in responding.

Due to the nature of this matter, your enquiry was referred to a specialist for investigation and response. I can now provide you with the following advice:

Speed limits are set to provide an appropriate balance between safety and mobility, with consideration given to factors such as the number of access points along the route, the nature of the road environment, adjacent speed zones, road user types and the crash history.

We have assessed the speed limit on Nepean Highway, taking into account the above criteria, and found that the current speed limit of 80 km/h is appropriate for this stretch of road.

This assessment notes that the safety record on Nepean Highway between Uralla Road and Forest Drive has improved since the federal funding allowed the implementation of upgraded line marking.

Additionally, we are aware of community concerns regarding the school crossing at Balcombe Grammar and supports a remote school speed zone. At this stage, this will be prioritised under a future funding opportunity.

We appreciate you taking the time to raise these concerns.

I then followed up with a call to get a translation.

According to the lady Jess I spoke to Balcombe Grammar is approved for a remote school zone. Because it is not directly accessed from the Hwy, it is not a normal school zone but a remote one. These require special funding and VicRoads has to request this every year in June or July and they wait 8 weeks to find out how much money they will get and then which schools they will be able to provide the new remote school zone to. Seems like that's all the information I could get, however, there is a team that sits under the south-east roads group in Vic roads that looks after this.

So although the school zone is approved by VicRoads there is no answer on when it will be built.

In the case of the stretch of the Nepean Hwy the idea to change the speed limit has not even been considered as it is seen to be appropriate for the road. Need to get more info on that one.

The big question about when are the planned upgrades happening was met with not much further information but that it is in the planning stage and that there is no one responsible or a timeline available. 

I think the lack of appetite to get this project going quickly has something to do with this and I quote "This assessment notes that the safety record on Nepean Highway between Uralla Road and Forest Drive has improved since the federal funding allowed the implementation of upgraded line marking."

So some answers but not much clarity on the situation. Will play some think music unless anyone else has any ideas???