SAMSUNG S6 WORST PHONE EVER

Im a very unhappy user of the Samsung s6 handset I purchased the handset last year end of August then i worked for +- 3 weeks then it would not switch on , Ithen took t ha handset to Samsung assuming it would be repaired faster. The handset was repaired and i got it back within a week. Now the same handset about a month back would not allow me to access any applications on the phone it read \ unable to open applications you can only use 1 app which is too make calls. I have gotten an EMAIL stating that the handset will be fixed if I pay R1606.67 for the SUB & REAR case what ever that is. I find it ridiclous that I must pay for a faulty handset which ever since i got it it has given me problems. I have been a samung user from the Samsung s4, note 3 but now i regret buying a Samsung."