During last year’s online shopping festival, Rajasthan-based Pramod Goyal shortlisted a mobile phone priced at Rs 33,000. He saw that there was an additional Rs 3,000 offered as exchange discount for an old smartphone. He did not have one, so he bought his colleague’s old mobile for Rs 3,000 and gave it in exchange. His total discount looked like this: Rs 3,000 for exchanging old mobile, Rs 5,000 as the value of the old phone that the e-retailer paid, Rs 3,000 as an upfront discount, and 10 per cent more as a discount on his bank card. He ended up