Paytm Mall - Smartphone missing from package

I have ordered a Redmi Note * Pro (*GB/***GB) smartphone coloured Aurora blue on ** Nov **** and paid ***** using my credit card. The package was delivered to me by Ecom Express courier executive on ** Nov ****. I kept the package in sunlight and left for some work outside. I came back around ** pm and then opened the package after sanitizing the same. When I took the brand box out I found the seal of the same is broken and 'S' was written on the top of the box. I opened the box and found the charging cable, power adaptor and sim tool but no handset was present in the box. Unfortunately, I didn't record the unboxing video. I quickly raised a return request on Paytm app and attached an image of the contents of the box as well. This request was placed on **th November **** night. They also showed that return pick-up is expected on ** Dec **** and refund is expected on ** Dec **** to my credit card. But after that, there was no communication from their side. Then I tweeted about it and tagged Paytm mall care. They asked for images of the outer and inner packages from all angles and also asked if the package was tampered and about the presence of bubble paper in the box. I sent the images and told clearly that the seal of the inner package i.e. brand box was broken. Initially I couldn't find the bubble paper but later found it deep in the outer package. It was not wrapped around the box as it should have been. And most of the bubbles were collapsed as well. I took the image of that bubble paper and shared with them as well. After that they were silent so I had to tweet repeatedly and got the answer like there investigation was going on and they would update me soon. It happened over few days and in the meantime I found a lot of complaints about Paytm mall over social media and almost all of those were not resolved. I really got worried and finally on ** Dec **** they rejected my return request over the paytm app and twitter as well. They cited reason like as per their investigation the order was delivered correctly. I responded and asked for clarification but they replied that nothing could be done. They made me look like a liar where actually they cheated and looted me.