Regarding the conditions put after taking the policy

I have a ReAssure policy from Niva Bupa for my mother that policy does not mention any limit on cataracts on the amount or on what types of lenses we can use

Now the insurance company is saying that they will only cover the mono-focal lens only this is their internal policy and I am like the insurance is a contract in which I disclose everything in utmost good faith you as an insurance company also tell your conditions on the policy wording

But can't deny us or limit us which is not in the policy wording

And one more thing you can't deduct 44% claim amount in a cashless claim no hospital will give you such a significant discount on any surgery whatever may be the reason for the package MOU even if you mention it on the pre-auth letter rest is deducted do not collect the money for the patient the hospital will definitely deny offering the cashless claim

What are your opinions?

I thought the insurance policy wording is the binding contract no one can add any additional conditions till the renewal