I understand in some contexts they cannot be interchanged, for example, one can say 'the price is reasonable', but 'the price is justified' sounds incorrect.
But I don't know what are the exact differences between them when expressing 'something is reasonable or proved to be reasonable". To me, they seems to be interchangeable in most situations.
In addition, I learned that 'warranted' in some context also means 'reasonable', for example, you experienced a degraded service and then requested a refund, you can say "I feel a refund would be warranted". Can I use 'reasonable' instead here? Is there any slight difference that makes 'warranted' better?