Also, something is wrong with your example. Cost of buying the original platform is $X, sales (not revenue) for multiple years is $3,500, fixing it or replacing it by a compliant platform is $Y. A "fix" is clearly not more expensive than $X and that was much, much less than the revenue from the sales.

Also, it seems to me that the original product was defective (illegal), so why should she have to pay for the fix?