damaged cellphone

I reported a cellphone that was bought on January 2015 around March it was no longer switching on and they collected it and it stayed three months with them and send it back saying that it was repaired but ws not working and I send it back for repairs again and it was repaired and it only worked for three months and now no longer working. I reported again they said that they will come and collect it since the 8th of this month nobody came to collect the said cellphone. Their service is very poor. I'm fed up and dnt want that phone again.