Bad after sales

I purchased a Helicopter for my son FROM liberty midlands mall branch. He opened the toy on Christmas morning. It flew twice adn went dead. When we tried to charge it. It wasn't charging. On 26Ddcemever I took it back to the store. They requested the box. Which had already been thrown away and the slip which i didn't have I said I would get a bank statement. Ever since then I have been in store weekly trying to get a replacement or my money back. After sales service is very bad. Plus they are selling these toys for so much but they are clearly cheaply made.