Flipkart - Blocked my account

I have bought Oppo F* mobile on Flipkart in May ****. Along with it I have also bought buyback option which will start from October **th. Few days back they blocked my account stating that I have bought number of mobiles from my account and I have sold them to other people. Stating this reason, they blocked my account. I have bought number of mobiles, I agree. I didn't sell to others. At my home, not everyone knows online shopping. So, my relatives call me and ask me to place the order. They could have locked my account. They could have warned me atleast once. Or they could have sent me an email telling that this is the quantity u r allowed to purchase from ur account. I have comfortably placed order. When the time has come to avail buyback offer, they silently blocked my account. I thought of reaching them. But they are simply sending the same email again and again. I have asked them to call me atleast once regarding this issue. No one is replying either on social media or email or call. They promised me Rs. ***** for my oppo f* mobile. Now they blocked my account and I can't avail the buyback option from other account. If I try to use it from other account I will get around **** which is ***** Loss for me. Likewise there are other mobile which have buyback option. They allowed me to purchase the mobile and then they blocked my account stating I have bought more number of mobiles.