Efficient modeling of Eddy Current Testing (ECT) signals is needed in many areas of industry. Probes design may be improved, and experimental signals interpretation may be better understood by using dedicated numerical simulation tools, provided that they are computationally effective and accurate, while remaining easy enough to be employed at end-user's level. A Boundary Element Method (BEM), dedicated to the numerical simulation of ECT signals due to complex narrow cracks affecting a Planar Multilayered Structure (PMS) and presenting arbitrary orientations is investigated herein. The theoretical formulation relies on the calculation of the dyadic Green operator, associated to the PMS, via appropriate vector wave functions expansions. Then, the use of the Discrete Complex Image Method followed by the application of the Generalized Pencil of Function (GPOF) method is proposed for the efficient computation of this operator. Validation results of the complete model, by comparison with experimental data in laboratory controlled condition and with data provided by a finite-element code, are presented and discussed.