For example If there is a deficiency regarding lack of segregation of duty in xyz Department, in that situation what recomendation to write??? and any test of control for that recomendation???
Duties do not have to be segregated in a department so much as between individuals. A general recommendation would be to have independent review/check of some aspect of the work carried out by the individual whose responsibilities are not sufficiently segregated. The test of control would then be to review the evidence of that review/check.