How to add a number after the internation prefix

How to add a number after the internation prefix

Hello, I have one problem and only happens with the Mexico code phone we have installed the WhatsApp Woztell in our zoho crm, when a lead send the phone number the lead send automatically the international prefix +52 xxxxx xxxxx. But WhatsApp don’t detect this number because WhatsApp need only for Mexico put the númber “1” after the +52. 

How can I create a function that change the number from +52 xxxxxxxxxx to +521 xxxxxxxxxx

if hope someone can help me with this. 

Regards