Leroy Merlin useless

I bought an inverter online, thinking that it was AC-DC , then 3 days later I went to Leroy Merlin Edenvale, and I was told that I should go back with the item and do the return online or respond to the email that I got when the order was send, I did as i was told. Ever since I have been sending emails with no response. Recently now they send me their terms and conditions of 7 days return policy.Spoke to numerous so called helpdesk of theirs with no hope and solution at all, I call speak to different team member and explain my story while they have a system i am so angry right now.