Uber — for no reason cancelled my free trips

Address:

Bangalore, Karnataka

I had got 2 free rides worth rs.600 each from uber as part of its promotion policy. I had referred uber to two of my friends and they downloaded and used uber so I had got 2 free rides. Also I had confirmation mail from uber saying I have got free rides. but when I tried to use those free rides suddenly all the free rides were cancelled and I was charged money from my paytm wallet. and when I complained about this issue to uber, I was told it was system error and they cannot help me on this anymore. please help me