Boring one, apologies!
The scenario: say you’re ordering a pricy tech item.
Amazon (sold by them directly) has it cheapest. John Lewis charges 15% more, but have an additional year of warranty of course. This could very well be useful - I’m actually ordering this item to replace my current one which is faulty.
Would you order from John Lewis for their extended guarantee; or would you go for the cheaper price at Amazon & rely on their generally good customer service?