Bad client service (misleading clients)

On the 19th of March I bought a laptop from your store in canal walk. I was assisted by Dani. I told him what I would be using the laptop for (Adobe software) and he recommended something with a good graphics card: the Lenovo gaming laptop. On the day of purchase he told us that if we were not happy with the laptop within 7 days we could return it. I used the laptop this week and was very unhappy with the battery life. It lasted me a maximum of 3 hours each day before I had to charge it. On the 25th March I came to return the laptop and was told that there is a 15% handling fee. I was not informed of this on the day of purchase and was told that I should have looked at the slip. I spoke to the manager, Amien, as I was displeased with what they told me. He said that customers should know this policy. I personally feel that I should not be charged a handling fee as the battery life is shocking considering it is gaming laptop and I'm not using it for games at all. I feel misled upon purchase the laptop as I was not informed of this and apparently I was just supposed to know.