Truworths employees not trained in cellphone sales

I bought a Huawei cellphone that does not support google (this was not explained to me)... When I went back the following day to exchange it they said they can't ( I was told by the sales lady that I have 7 days to return it if I was not happy, and now it is said that it only works if the device malfunctioned)... I will not pay for this product as it does not have the functions I require...