Insurance

I report Lewis Gobabis last week, I have my own insurance and want them to cancel the insurance on my account. This is going on for three months. The manager of Gobabis just phoned me and explain very rudely to me that this is the way they work and I just need to except it. My problem are that even when I purchase the furniture they did not told me how the insurance work, and even though I've been asking them for three months, the manager told me this afternoon that although she's been working for Lewis for years she did not know how it works, but I need to except it because it's been working like that for years. My question are : why do I need to pay almost N$14000 for insurance to Lewis if I got my own insurance that cover everything.