Spicejet - Extra money taken for stuff literally bought from the airport duty free

I recently took a flight from dubai to delhi via spicejet and my experience was terrible. Everything was fine until the boarding started. At the boarding they started weighing our stuff which is ok and acceptable till the cabin bag, but they also weighed my backpack and the stuff i literally bought from the airport duty free. I have never seen any other airline counting weight of the stuff bought from the airport. Taking weight of the cabin bag was acceptable and mine was also in the limit of *kg but they also weighed the other stuff and asked me to pay an extra ₹***** for the weight. The ticket for the flight was around ₹*****, so you can see what the problem is here. I am a student in dubai and rather than helping me when i told the staff they targeted and intimidated me. A man from the staff literally took my ticket and told them to offload my luggage when i complained to them. I was basically forced to pay so much extra, i could have literally travelled in emirates businesses class in this much. I was coming home after * months and i did not think anything could ruin my mood but spicejet congratulations you managed to do it. Thank you so much for showing me what a terrible airline spicejet is and you can be sure i will never be using this airline again. I dont even think anyone at spicejet is going to read this, nor reply to this because spicejet probably has no answer and has proved itself incompetent to me.
Flight number- SG***
From Dubai to New Delhi