Defect iPhone

I bought a preowned XR at incredible connection evaton Plaza last Thursday with a battery life of 82%. Saturday, Sunday I went to the store with this issue with no help to my avail. I then went yesterday after I experienced a hyper battery drainage which meaning I went 3 straight days in a row… when I got there wanting to exercise my rights as stipulated in the consumer protection act of 2008 and in the lay buy contract that within a 7 day period I can get a refund or exchange they said no and wanted to only subscribe me to a 21 days max waiting period. The battery defect thing carried out like a warranty claim than a defect case…and I was told that I must not forget that is pre-owned😩😩😩

I would never recommend one to go that store…the terms are there for deco.