Uber India — not applying promo code/gift code

Address:	Kamrup Metropolitan, Assam, 781007
Website:	help.uber.com

Sir/madam,
It is to inform that from the last few months the promo code/gift code which is received though sms doesn't work/applied in my uber account against mob no. [protected] and shows "promotion codes are not available for this account and all trips will be charged at the full price".
Recently i have received a promo code "gold50" valid for 13 august, but still it is also not working.