Good morning curious about my Isx15

[Nhramember]

Good morning everyone I got a 2015 kw t680 and in 2022 put a new egr cooler, doc,def filter. I just put new injector and fuel pump head about 2 weeks ago. I took a trip to Jacksonville Fla and got the code saying dpf when I hooked up insite. I took down the doc and dpf and took it back to the shop where I bought it. They baking the doc said it’s good and they say dpf has an internal collapse. They saying it has a1year warranty just past my 1year but manufacturer said send it back . They would check it out and see about warranty claims. They say my only options buy a new one get a refund if they warranty it which can take up to 15 business days . What causes internal failure on a dpf filter. It’s not pushed out or anything? Let me know what y’all think thanks Nate.