waxpro

My non-o (family) will expire on the 29th Oct. due to some reason to travel to Phuket tomorrow for a week, went to the immigration office today to make the extension for 60 days earlier to avoid rush time, when arrived back home from the immigration I discovered they stamped the extension till 20th Dec. I expected the extension will be counted from the expiry date, not from the date of stamping/applying for extension, My question: anyone here had the same mistake before? and how to correct it? as for today is Friday, and tomorrow is Saturday (office closed) and I will be flying to Phuket, will return Sunday the 30th, shall go to the immigration office again to explain this mistake and ask for correction? or any advise about this issue? Thanks