Bad Service

On the morning of the 28th of March 2019 I went to Cellucity Melrose Arch to buy a Samsung S9 Wireless charger. I then brought it to my workplace and started using it. Atfer 4hrs the phone only had 40% battery and yet this is supposed to be a fast charger. I then went back to Cellucity to return the charger. The manager, Lee Hancook, asked me to fill in a refund form, took my card details and assured me that they would return the money to me by the 5th of April 2019. Since then I have not heard from Lee concerning this refund. I went to the shop again today and Lee informed me that she had submitted all the paperwork to head office and was awaiting their response. It's been over 7 working days now and I still have not recieved the refund. Lee decided to tell me that they do not do refunds and she will not be able to help me any further. She told me that she was too busy with other things hence she did not bother to contact me with any feedback. She told me that it is my responsibility to follow up with their head office since I am the one in need of a refund.I do not understand such customer service because they sold me a malfunctioning charger. May you please intervene in this matter as I am waiting for my refund.