DPF HELP

I am having trouble with a DPF system its a KW 2014 ISX
Initially I was told it needed a new dpf filter or to have them baked so we had them baked.
Truck was giving codes 22754 3376 1922.
Mechanic had them cleaned and also replaces the Differential pressures sensor
Truck ran fine for a few hours but it kept wanting to do a regen every time I would stop at a light it would give me the hot exhaust sign. I stopped and did a manual regen then took off. After a few more hours red engine light came on and truck lost power. I took it into the same mechanic and he took the filters off and had them backed again blaming the cleaning company that they might of no done a good job.
after the 2nd cleaning I took it for a test drive and within 15 mins of driving it it gave me code 3251 and kept wanting to do a regen same as before. Mechanic is saying that the DPF Inlet filter is coming apart and needs to be replaced with a new one. He thinks the DPF filter is still good. I bought a new one about 8 months ago.
The question is how often does that DPF inlet filter go out? I have heard of changing out the DPF filter but will the Inlet filter reallt cause all that trouble??

 

Yes he did both times and he also did a forced regen after and no codes came up everything seemed fine
until we ran the truck both times truck has about 625k miles and like I said dpf was replaces about 8 months ago. DOC has not been replaced.

 

He said he checked the egr and the turbo and the Vgt turbo actuator he suggests installing a new DOC filter
He will remove them both tomorrow I am going to see them personally

 

I must add he did not charge me for taking them off and cleaning them a second time.
It seems like the truck is always trying to do a regen on its own

 

Yeah at this point with all the money I have had to put into these trucks and the dpf systems
most likely I am going out of business. Id rather just return the trucks and deal with the consequences
I bought them from Kenworth with about 400K miles each and since day one the dpf systems on this trucks have been nothing but trouble. Kenworth them selfs when I first bought them would not bake the filters. I was ignorant engouh to not really think it through and just say okay.
I have two trucks exaclty the same type of truck Both have had new DPF Filters right away when I bought them both over the road spend about 4K each time