OBF booked for repairs

I bought a Nokia 5 at Markham Vangate on the 24th September, i experienced that the battery drains dramatically without even using the device. I would charge it full at night before i go sleep and when i wake up the battery will be on 47%. I took it back on the 29th. Note: im still within my 7 day OBF period. The consultant at the Vangate branch said the only thing they can do is book it in for repairs. I then said its fine as i did not have knowledge about the 7day OBF period at this time. It came back from repairs on the 13 October 2017. They advised me that the phone was not repaired because no faults were found. I then went to Markham in in Maynard Mall and they explained about the OBF and advised that it was supposed to be booked in that way. I bought the device cash for R2999 and i barely used the phone because of the battery life that didnt even last a day on a full charge and i didnt even download any addition apps only a Antivirus.