Opened up box to find no device e

I purchased 2x hisense sero 8 pro tablets from the Springfield branch on Monday 30/11/15. At the time of purchasing the plastic film on one of the boxes was open. At the time I didnt think much of it because the sales assistant didnt think much of it so I assumed all is fine. When I opened the the box two days later (2/12/15) Lo and behold one of the boxes was empty but for the charger. I immediately called the branch to inform them and was told by marcell at customer service that I must come in to have it changed. When I go into the store about 2 hrs later they tell me there is nothing they can do for me. Am I supposed to just lose out like that. They insist that the footage shows 2 sealed boxes being handed to me. When asked to see the footage, it is such low quality grainy images. How are you ever going to see a clear film of plastic in that. They can't prove that it was sealed. I am taking this up to consumer protection as well as with my legal advisor. Please have a look at the footage and see if I look like a ****. I had purchased for my two young kids who you can see on the footage are all chuffed but now sit with broken hearts. I will not rest until I get my right