What should my friend do about her visa overstay during Songkran holiday in Thailand?

A user is seeking advice for a friend who has overstayed her visa by one week in Thailand during the Songkran holiday. Several comments suggest that immigration offices are open during the holiday, and recommend that the friend should visit the immigration office to pay a fine of 500 Thai baht for each day overstayed, and apply for an extension. However, there's a warning that the immigration officer may deny the extension application, in which case she would need to leave the country within 7 days. Another option mentioned is to buy a ticket out of Thailand and pay the fine at the airport, while cautioning against checkpoint inspections.