Mail Slot for Stucco Wall

[Tumbleweed]

Need to replace the Mail Slot Cover present on a stucco wall. The original mail slot is narrower than any of the new stuff I am finding.
What method for cutting the stucco to make the slot wider ?

I appreciate all suggestions, recommendations, and feedback.

 

[Snoonyb]

Rent an angle grinder and a masonry blade.

 

[Tumbleweed]

Brilliant & simple solution, many thanks