Wich one is correct?
Before that, I have completed two QQI Level 5 such as English, Business and IT as well as PC Specialist.
Before that, I had completed two QQI Level 5 such as English, Business and IT as well as PC Specialist.
The use of "have" is incorrect here. The use of "had" can be grammatical, but it doesn't quite fit the context. Instead use: "Before that, I completed....". When listing your accomplishments, you want to be concise and use the most active voice possible.