You do not need an Advocate to draft a Section 138(b), NI Act notice. A hand written note mentioning, i) the amount under subject, ii) cheque nos., iii) dates of issue, iv) bank particulars, v) details of dishonor, with a demand for repayment, is valid for the purposes of calculating relevant limitation periods.
In Pawan Kumar Ralli v. Maninder Singh Narula, 2014 (9) SCALE 327 it was insisted, a formal legal notice was real and not the hand written note. The contention was rejected in view of the law laid down in Central Bank of India, (1999) 8 SCC 221. A Section 138(b), NI Act notice has no prescribed form.