Fault after dpf refill.

[Scrappy LS]

So we recently had an error flash up on the screen saying dpf refill needed.

So I brought some stupidiy expensive dpf refill and got a garage to refill it and he also reset the warning.

Now 2 days later and the engine has started being very noisy when driving but sounds normal when idling.

I took it back to the garage and he has said that it sounds like the injectors, and that they might need recalibration.

Is this normal? Has anyone had this issue before? Or is the dpf a red herring and the injectors are genuinely out of calibration?

Tia

[Scrappy LS]

Just to add, it's a 2013 3008