Broken promise

I bought a home theatre there late last year bt earlier ths year stated experiencing problems with it took back and they couldnt take it back because we were goin for lockdown so i took it back home en waited and when we were on level 3 took back again and they promised to fix it and after 2 weeks they brought it back and it was still faulty en i took it back and again like last tym after two weeks back brought it back and it was stil with the sam fault en i phoned them and they came to collect it and now they sent back another one saying its new but they did not send the correct cords to plug it in now i cannot even see if its working...this is realy upsetting me as i bought this for my mother