Damage tablet

I bought a tablet in December 17th and it worked perfectly on 19th when I was suppose to charge it couldn't charge unfortunately my child was on holiday with tablet in PE and papers where in Cape town so I couldn't get the tab to the store until she came back. I called the store informing them that the device stopped working and I was told unfortunately it's gonna have to be booked in. I was told it will take 14 you 21 days it's almost a month now. When I came to the store sat I was told to come Monday 29th I decided to come 30th now I'm told the tablet is only leaving whenever but it's still at the store. My child needs this for school no one is bothered cause they are not the supplier. What do I do I travel. The store manager told me I should've a backup for my child. What back up he has backup he has the means for backup for his kids I don't. Please help frustrated