Cell C refuses to replace a damaged handset

In 2014 I entered into a 24-month contract with Cell C wherein the handset, a Sony Xperia C C2305, was delivered on the 1st September 2014, and the line was subsequently activated within 24 hours. On the 19th November 2015 the said phone just went dead, and I immediately took it to one of Cell C's branches in Hatfield, who booked it in for repairs. On the 27th November 2015 I received a call that my phone was back but it could not be repaired since it was out of warranty and the repairs would cost more than a new one. I then contacted the repairs department who confirmed that they cannot repair and/or replace the phone. According to the report received from SSS cellular repairs, \the handset is deemed BER due to main board dead". Cell C has advised that they cannot replace the device since it was out of warranty of 12 months from Sony"