Nissan Xtrai 2015, 1.6DCi DPF always having DPF Problems.........

Nissan Witbank replaced the DPF of my car , 2015 1.6 DCi Xtrail in April 2019 and charged R52k, 10 months later the car had the same problem, they fixed the problem and 6 weeks later the car is non drivable, i am worried about the quality of their work and parts. did they really replaced it or just cleaned and used the old one after charging such a lot of money. if it was replaced then it means i must be prepared to pop out R52k every 10months? is there any proof of replacement? Why is this DPF always a problem?