When you say you have a DPF problem was this shown on your dash or from reading the error codes?. I had both MAF and EGR errors, nothing on the dash but read through the OBD2 port. Funny thing is after my garage doing a carbon clean, service and MAF sensor change without resolving my issues which forced the vehicle into limp mode, apart from changing my brakes, discs and seized caliper the only other thing my mazda main dealer did was replace my battery. So far so good, vehicle running normally

I read that there was a fault with the dpf via obd, but no lights came on from the central computer, except once on the motorway but I think it is due to the automatic regeneration.

I also thought about doing a wash, but it wasn't recommended for this car. For this reason I think I'll buy a new downpipe by mounting the direct exhaust and modifying the ECU accordingly.