Full disclosure not given when purchasing a Samsung product

I purchased a Samsung Galaxy Tab 7in for my 85 year old father who wanted to upgrade to a better tablet. I was not fully informed of the phone. It has a double tap function and four steps need to be taken when making or receiving a call. This information was not provided to me when I purchased the device. When my father wanted to use his tablet, he found he could not manage the double tap function and was getting flustered. Subsequently he has not been able to use his new tablet. I went to Samsung two days later, hoping this function could be removed, but was told I needed to go to the place that sold me the tablet. Vodacom 4U Woodlands told me they were not aware of this function of the tablet but would not exchange it. This is withholding crucial information vital to the functioning of a device sold by the store. I was told by the manager that the sales consultant and no other personnel (including the manager) were aware of this very frustrating function of the tablet and that it was not their job to know about it. Their job was just to supply the product. Please be very careful when purchasing a Samsung Galaxy Tablet 7 inch. Nobody has the time and/or patience to have to go through four steps to just answer and/or make a call, especially not an 85-year-old. I fail to understand how you can sell a product but not know anything about the functionality of it. I have had no joy in getting my father sorted with a tablet he can use. I went back 2 days after having acquired the product but was basically told I have to 'suck it up'