Hi Subbu,
Hmm... I'd be inclined to create an intent for changing their mind (eg. "I want to change my selection", "Sorry, not registered, TFSA", "I made a mistake", etc) because they could realise they have made a mistake at any point in their conversation.
You can then use dialog nodes and entities and further questions to figure out what mistake they have made (eg. They mention TFSA, you match a "@request-type" entity so you know they have made a mistake regarding the request type and can say "Do you want to change your request type to TFSA" or if you don't match an entity type you default to asking what they want to correct and going from there.
Regards,
Graham
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Graham Walker
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