There is no ban for the Xiaomi phones. The court order is only to suspend the sale and import of their phones to India due to some patent issues with Ericsson. This is expected to be sorted out soon. Also, the Delhi Highcourt order doesn't talk anything about the existing customers. If you already purchased the phone and have received it, then there is nothing to worry. You are safe to use your Xiaomi phone.
If you have placed an order and haven't received it, then it is possible that company may not be able to ship it to you. Check your order status with online shop and see what it shows. You may want to call them and ask their shipping plans.
Their future sales would be suspended until they are able to sort out the issue. So, it is possible that you may not be able to order the phone until the company is able to clear the injunction order from the court.