Different laboratories use various methods to measure CEC, and can return contrasting results depending on the fraction of the soil measured. please have a look the following:
@ Irfan, I think ammonium acetate extraction is also viable for peat/acid soils. Place 3 grams of 1 mm air-dried soil sample in a 250 ml erlenmeyer flask, and add 100 ml of 1 N NH4OAC (pH = 7.0) solution.