Accused of using items then returning for refund

Okay so i received a pair of sunglasses as a valentines gift. Which came with a \luxury bling care kit\". Which was paid for by the way. So in this kit is a little bottle with a solution that you're supposed to use when you're cleaning your glasses. Which you obviously shouldnt need to do to a new pair of glasses. After about a month i decided i'd give them a clean. Only to realise that the little bottle was empty. I looked inside and the bottle seemed to be empty from the time we got it. There were no droplets of solution so it was clearly empty from the shop. I went back to the store, told them my story and i was then accused of using and finishing all the solution and now coming back to get a free refill. What? If I've spent R2000 in your shop why on earth would i come back claiming that my solution was empty and demand another one? If i paid for something i expect to receive it! After purchasing 5 pairs of sunglasses from sunglass hut this is the worst service I've received. And unfortunately it will have to be the last time i ever shop there again. Thanks to the useless and unhelpful staff. "