Under 60D(3) of the Employment Act quoted below, it only mentioned payment when required to work on public holidays but that sub-section is silent about replacement. Replacement is only allowed as mentioned in sub-section 60D(1B) like sick leave, SOCSO cases and so on. However, if you are not covered by the Employment Act, replacement is purely an arrangement between you and the company. Consult the Labour Department if necessary.
"(3) (a) Notwithstanding subsections (1), (1A) and (1B), any employee may be required by his employer to work on any paid holiday to which he is entitled under the said subsections and in such even he shall, in addition to the holiday pay he is entitled to for that day:
(i) in the case of employee employed on a monthly, weekly, daily, hourly, or other similar rate of pay, be paid two days' wages at the ordinary rate of pay; or .."