I want a newphone or my money back

I went to pepcell semimarks on the 14 november and bought a phone for my son the lady who was assisting us told me that the phone can be refunded within 14 days if it has technical problems...so on the 20 i went back because the phone has lines on the screen but i was not refunded the phone was booked for repairs and the repairs will take 30 days.i want a new phone or my money back