DONT BUY PHONES FROM CASH CRUSADERS- ITS A TRAP!!!!!!!!!

I bought an iphone at Cash Crusaders Hatfield, The phone had a faulty screen and the proximity sensor was not good, have only been using the phone for a month, literally. I asked if i could return the phone and i top it up to get another phone, they refused. they said the phone needs to be completely damaged/ unusabl. Im really dissatisfied with the phone- i asked them if i was to reset the phone and it happens to icloud lock- what happens ?, they said they won't refund me even though i'm exercising my right as a consumer to use what i bought from them however i want to, it seems limited to how much i have to use it and if anything happens- that is not caused by me. i wont get a refund. EVEN THOUGH IT HASNT BEEN SINCE MONTH YET. I AM WITHIN THE POLICIES THAT ALLOW ME TO GET A REPLACEMENT