Unfortunatlly as for problem with the dates of the visa
I had to do it today with the bus (273)...

NOT RECOMMENDED AT ALL !
Never Again!

3 hours trip Buriram - Chok Chai (ie; korat immigration).
The bus is old,smelly,sticky and noisy.
The bus stops every few kms for people.
Fill the bus till no space at all.
Buriram -Nang Rong - Chok Chai.
You need to get off from the bus on the traffic lights on the side road and walk 1 Km.
*The way from the bus to immigration we took Taxi 20 Baht/each person but the way back we walked from immigration back to the same traffic light to catch the bus back to Buriram. (No taxis near immigration office for somne reason).
Luckily we met a friend took us back to Buriram with the car.
Immigration documents; Need to add and remind that you HAVE TO BRING YOUR WIFE ALONG WITH YOU.
There are few new forms of questions for the wife about your relationship and life together..
It's in Thai and there is a very lovely lady there in the information section, very helpful.
Costs:Bus tickets Buriram-Chok Chai = 180 Baht (Go & Back) x 2 people = 360 Baht.
Motorbike taxi in the traffic light = 40 Baht.
Total cost = 400 Baht.
Estimate of time wasted = 8 Hours all included.
My advice:Do yourself a favor & save yourself a big headache:
Go with your car or use "Buriram Expats" Visa Run service.
(Up to 4 people all together).