Harvey Norman don't have a good track record on dealing with returns. They've been fined quite a lot over the past few years for making misleading statements about what rights you have and responsibilities they have. Things like insisting they get to decide on the way the issue is remedied. Insisting on store credit etc.
Hopefully, the stores are better educated now (the above stuff happened a few years ago) and you will see a good outcome. Also people higher up the management chain are generally more aware of statutory responsibilities so it can be worth asking to speak to the manager as you may get a different answer)
But in general its much more expedient if you can wrap up your claim under the extended warranty agreement. Talk it through with them, if you feel you're getting a fair deal then go ahead and accept their offer. If not, then there are other options (Legally they owe you a prorated cash refund if you want). The difficulty is that 'prorated' bit. But just know that there are options if you can't agree.
Read a bit about it here (NB I don't want to alarm you as I'd almost bet you'll have a good outcome. Just good to know you've got options)
The warranty is the extended warranty from Harvey Norman.
The model is as per subject title Panasonic TH-P65VT50A Plasma and was purchased around May 2013 from memory. I'll heed your response and put this detail in the body of my original post.
I suspected as much so am hoping to get an equivalent calibre of screen for what they offer.
Will report back once I know my budget.
What warranty process are you using? Original manufacturer. Extended warranty? Statutory warranty?
Also how old is the TV and what model?
After several years it would seem unlikely the store will reimburse you the original cost. Usually they start buy offering to replace like with like (if no actual replacement exists) and then talk $. The good news is that 65" screens have come down in price a lot over the last few years so you'll probably be able to get a good replacement for much less than you last paid. Don't go bigger than 65" as you will start to pay a hefty premium for the increase of screen size after this point.
Might be a good idea to see what the store offers to give you as a working price as there's little point in suggesting TVs unless we have a ballpark $ to work with.