Asking for double amount as security deposit without informing

I purchased a product from Anvi Fashion Collection. Later I was asked to pay an additional amount as a security deposit, which was double the amount of the product cost. This additional payment was demanded without informing me in advance, and no proper explanation or further information was given about why this extra amount was required. I find this to be a misleading practice, as the actual cost and conditions of the purchase were not clearly disclosed to me at the time of buying the product. I request that the seller be directed to stop this misleading practice, clearly disclose all charges and conditions before sale, and take back the extra security deposit amount charged from me without proper information.