Underpinning advise/help needed

Our 1928 double brick house on clay has developed some bad cracking in both internal and external walls.
Looks like the front corners are dropping away plus the side walls likewise.
I’ve had 3 inspections/quotes re fixing.
All different methods proposed and I need to choose which to go with.

The new eurathane stuff down small holes but fills everything and migrates to any void in the immediate neighbourhood.

Traditional conc/grout in 300mm auger bored holes, about a dozen strategically placed.
Problem is in this old a house which probably doesn’t have conc footings what’s to keep The integrity of the foundation. Will some be fixed and other parts sink again.

Lastly quote saying the sagging isn’t that bad and tying the brickwork together with steel bars across the cracks.

Has anyone any experience with a Sydney company doing this sort of rectification work.
H.

A bloke I used to know did the gealogical assessments before the work actually began on blocks before building could begin. I can't remember what he was called but it was a speciality in geology and I would suggest if investigations of this nature haven't been done then it is a lot of guess work that might not fix the problem.

I agree with Chris - I've been through a similar process with our house on a steep slope and ancient foundations. Had several foundation 'specialists out to look, and felt that they all made a very simplistic assessment with simplistic solutions.

A great idea is to check whether you're in a mining subsidence area (practically everywhere here is!) - [email protected] | www.subsidenceadvisory.nsw.gov.au . Even if you don't think the damage is due to mine subsidence, if you're in a subsidence area, submit a claim and they will come out and do a comprehensive survey. They also have contacts with skilled and experienced people that they use to correct issues. You won't be charged for the submission/assessment or any related surveys, whether it's assessed as subsidence damage or not.

We ended up with a survey (lots of useful info), followed by a full geotech survey, and a contact chain of recommended people to engineer the fix, and carry it out. (our issues are not related to subsidence).

Don’t spend too much on it, a house that age in Sydney would likely be a KDR in a few years time for whoever can afford it, patch and paint and go on a holiday with the rest of the money. ( when the borders open).
I did a lot of remediation work on Burwood girls high school a few years ago, they did the same thing, packing under the piers, chip off bad render and replace, and paint. When the engineer looked under the building, he said it could all move again come the next dry spell/ heavy rain.