Initially went to Hyundai who diagnosed a fault code of P0299 relating to under boost as a faulty turbo electric actuator.

The customer replaced the turbo actuator with a genuine unit, and although the fault code would no longer set, the vehicle was extremely underpowered, undrivable, as if in a limp mode.

Carrying out a full vehicle scan showed no fault codes, starting the car showed no warning lights, trying to accelerate was extremely slow, my initial thoughts were the DPF might be extremely blocked.