I have been involved in tuning for 20 years. Firstly, you have been deceived. Secondly, you must identify the issue, rectify it, and then remap or remove as necessary.Thirdly, they have exploited you, since they sell the inners or the whole DPF for hundreds of pounds, so receiving payment twice for the service.DPF issues may arise from several factors, including insufficient coolant temperature, inadequate fuel levels, and frequent short journeys, among others.