If the claim is for a Major Fault (and it certainly seems that it is) and is being applied for through the Store then they have to offer to you your choice of outcome, not theirs. ACL is very clear on that. You are correct on the replacement of a device in that it is a possibility but must be like for like (From ACCC site “Replaced products must be of an identical type to the product originally supplied”), however the supplier can choose to upgrade you. However as the Cooktop is no longer available and they don’t seem willing to upgrade you then it seems a refund is the only option left to you.
You are also correct that compensation is payable for costs incurred because of a major fault. If for example you had to buy cooking devices as temporary measures in my opinion you could claim.You would need to keep careful records of these additional costs and your dealings with the retailer. Phone calls are not the best way, letters, faxes & emails and similar where you have proof of sending them is important. The re-wiring of the device again in my opinion would be a claim that should be met.
Please understand I’m no legal expert or even trained in that area but a reading of the ACCC’s ACL breakdown in regards to Major and Minor faults seems pretty clear. I also think the retailer is more than likely going to resist the claim/s and this is where you need to get some legal advice on the matter and it would seem likely it will end up in a Civil and Admin Tribunal. In each State and Territory there is free Consumer Legal advice available. The link is to a list of at least some that are available but there may be more you can avail yourself of:- Free Legal Advice Centres.
Regarding Compensation:
If you are a member of CHOICE don’t forget they have a help service that can help you find the next steps you need to take.