??? to the dealer in question.
There is a Service Bulletin for GT roof's 2nd internal layer sagging which blocks the rear vision. And it is fixed with just clips. No idea why the dealer wants to change the whole roof. Sounds stupid to me. I gather Mazda will knock the dealer back.
See here for the relevant TSB:
https://www.miata.net/garage/tsb/Convertible%20Top-Inner%20Cloth%20coming%20off%20causing%20Poor%20Appearance%20and%20Obstructing%20view%20of%20Back%20Window.pdfOnly GT soft tops have this problem. Roadster soft tops don't have the additional layers. Yes there are 2 different soft tops!
The really disturbing thing I found when shopping for a ND was that I knew of all these TSB's before buying mine and the dealers did not have a clue what I was talking about even when the car right in front of them had some of the issues.
BTW
Link for all MX-5/Miata TSB's. NA through to ND.
https://www.miata.net/garage/tsb/Most are international so apply to Australian models.