What are the consequences of a 22-day overstay in Thailand and how can I avoid being blacklisted?

A user is seeking advice after accidentally overstaying their visa in Thailand by 22 days. They have received an extension from the immigration office in Samui and are concerned about the possibility of being blacklisted from re-entering Thailand. The user is looking for guidance on the repercussions of their overstay and any potential ways to avoid future issues.