A positioning map is only useful if customers drew it. Start with five conversations: ask why they chose you, who else they looked at and what nearly put them off (sample note).
Listen for the two things they keep comparing. Price is usually one. The other is the interesting one: speed, care, expertise, convenience. Those are your axes.
Then place each competitor where customers put it, not where their adverts say. Place yourself last, and be honest. The empty space that is left is worth a long look.