I agree the best solution is amicable. But, as the Yanks once said; trust in the Lord but keep your (gun)powder dry. What usually gets things done is the mailed fist in the velvet glove: talk nicely but let them know that you mean business and know your rights and how to enforce them.
If they do come around and agree to anything make sure it is writing. If they don’t agree and want to play silly buggers don’t hesitate to tell them you are aware of the Ombudsman and NCAT and though you prefer to deal nicely ( and even recommend them for their great after-sales service) don’t let them argue the toss, ask for contribution or ask for a delay while they do whatever.
You have the whip hand so use it. They want their money so will want to be obliging especially if it doesn’t cost too much. But, as well, if there is extensive damage you might consider also asking for costs to cover an independent inspection of the repairs.
Finally, even if there is a protracted dispute and you need to get an independent quote for repairs you should pay all but the cost of the repairs to the company with a covering note to say what you have done and stating that you still rely on their warranty and any statutory warranties regarding the quality of the system and the installation.
Good luck