As you have asked about the iPhone Citibank offer, I am giving you information about it, check below for the details
IPhone is offering cashback on purchase of the mobile phone through Citibank Credit and debit cards

The Offer is available on select stores

Model Category Additional Cashback (EMI & Non EMI transactions)
iPhone- 6S, 6S+ (all variants) INR 5000
iPhone- 6, 6+ (all variants) INR 3000
iPhone- 5S (all variants) INR 2000
iPhone- SE (all variants) INR 2500
iPad Pro (all variants) INR 2000

Features:

Offer is applicable only for transactions starting from 8th April, 2016 to 8th July, 2016
Offer is valid on both EMI and non-EMI transactions done by the Customer on valid Citibank Credit cards.
This Offer is applicable on transactions done on Plutus/ Pine Labs POS terminals only.
Applicable cash back will be printed on the charge slip issued to the card member
It needs to be retained for future reference and communication with Citibank.
Additional cashback available from the manufacturer on EMI transactions
Cash back shall be credited on or before 90 business days from the date of transaction