If you submit your 90-day immigration report late in Thailand, you may face a penalty of 2,000 Thai baht. This is the fine indicated by community responses for being 13 days late.
90 DAY REPORTING RESOURCES / SERVICES
Use the trusted Thailand 90 Day Reporting Service to get your in-person report done and mailed to you for as low as 375 THB (even if the online system doesn't work for you).
For immediate assistance, contact Thai Visa Centre directly via LINE at @ThaiVisaCentre or Email them.