If the insurance replacement industry is anything like it was in 2010 when I left it, you have little chance of complaining your way to something better. You’re right, the insurance company takes the discount so there’s none left for you to negotiate for.
It sounds like they’ve paid out at your policy limit for that type of item. If that’s the case, the only thing you could try is to find out whether the policy limit is voucher value or cash value. If the former, then demand cash to that amount and explain how you don’t believe you’ve been treated fairly. ‘Treating Customers Fairly (TCF) is a massive thing in FS in general and GI in particular. Talk about registering an official complaint and the ombudsman and you’ll be ok.
If the policy limit is the latter, you’ve had your lot I’m afraid matey.
Sent from my iPhone using Tapatalk