John is interested to buy a guitar to play as his hobby.He has a few brands to choose from and he is considering the price, quality, and design for each brand.John is asking advice from his friend, William who is a musician and he has recommended three good brands for John.

Who is the user, influencer, buyer, and initiator in this case?

Describe John's decision making approach using the lexicographic decision rules.

What would you suggest to John to overcome his post purchase cognitive dissonance?