Uber — Rejected free ride with unnecessary reason

Address:

Hyderabad, Andhra Pradesh

Uber providing referralcode for every registered user. If he/she refers any relatives or friends to Uber and when they registered with Uber with my referrall code then they will get first ride free and I will get one free ride. My relative registered with email "sree.[protected]@gmail.com" against uber used my promocode "pnc5due" When they applied it says promo code applied and they are eligible for one free ride. But upon first ride they deducted amount without giving free ride. When they reached about the reason they simply said they are using violation/inappropriate promo code. I did shared my promo code with another relatives they got free ride offer. Why it is inappropriate only for one person and not for others.