I have a website which do online recharge on mobile numbers. Currently, I have 4 options on website i.e. recharging amount lets say option A, option B, option C and option D. Now, I want if customer choose "option D" and recharge his mobile phone than a referral code would be emailed to that customer so that in future he/she can use it on website and get some % discount.
PHP/MySQL Experts needed. Should complete in one day.