Hi.

My retirement visa is due to be extended Friday 21st April

I cannot get to CW until Monday 24th April.

Is that going to be a problem?

Thanks for your help. 

A visa is not extended. You have an extension of stay based upon retirement.

You don't have to wait until the last day to do your extension you can do it up to 45 days early at CW. You lose nothing since the new extension starts from when the old one ends.

If you go on the 24th you will be charged 1500 baht for 3 days of overstay. They will accept your application after you pay the overstay fine.