What is the easiest way for a British citizen in Bangkok to extend a DTV for another 180 days?

Open your phone look on Google maps, choose a location to visit and look on sky scanner for the price. Not difficult

Do a weekend trip to Vietnam. The purpose of this visa is to explore and do tourism. Not sit indefinite in Thailand.

I drove from pattaya to ban pakkad border, 15mins and i was on my way back home. 700thb for fuel, $35 for cambodian visa. If you rent a car that would be 800-1000 for a day I think

Use skyscanner, destination: everywhere, get the cheapest flight out and come back. I don't know of any other way.

The round trip Bkk - Cambodia- bkk

Same day is less than 4000 THB

While the cheapest Border service by van is 3500

So what cheaper are you talking here ?

500 THB?

While it is faster and more comfortable!

Plus no Border service to Cambodia now

And the service to Laos Border is costly too and they don't charge DTV cases same as 60 Days visa exemption

Tuk tuk to Ranong

1.) Fly to Wattay Airport in Vientiane (VTE) from Bangkok (either airport: Don Meuang or Suvarnabhumi);

2.) Arrive at Wattay Airport and buy a Lao Visa on Arrival (Lao VoA) for USD $40 Dollars using Cash (crisp, "new", US Dollar banknotes) there and you will clear Lao Immigration at the same/adjacent counter at the far end of Wattay Airport Lao Immigration Arrivals area;

3.) Ride the bus from Wattay Airport to the Talat Sao (Morning Market) Central Bus Station to catch the bus from there (Vientiane) to Udon Thani Bus Station (the bus stop at Wattay Airport is at the far end as you make a right from exiting the Arrivals Terminal building);

4.) Since you have a DTV (valid Thai Visa/E–Visa), then you cross the Friendship Bridge into Nong Khai and go thru both Lao Immigration and Thai Immigration with the same bus;

5.) Arrive at Udon Thani Bus Station near CentralPlaza Udon Thani, then find your way to Udon Thani Airport;

6.) Catch a flight back to Bangkok from Udon Thani Airport

Don't try catching the Udon Thani Bus and trying to make entry into Laos (the Bus going from Udon Thani Bus Station to the Talat Sao Central Bus Station in Vientiane) as, even with a Lao eVisa, they won't accept foreigner bus passengers, unless you have already have a Lao Visa Sticker beforehand from a Lao Embassy/Lao Consulate in your passport, or, you have a passport from:

Russia, Switzerland, Luxembourg, South Korea, Japan, Mongolia, or ASEAN country

Go to something like momondo.com, throw in your dates, origin but no destination, find the cheapest return flight that isn't in Thailand and do that. Likely around 2-3000thb and will be far less work than trying to do 180 day extension or land border crossings. Can be a same day ticket if you don't want or can't afford to stay in the other country.

I don’t understand why you can’t just buy a return ticket to anywhere say Singapore go to the airport get on the plane, and come back, go through immigration and get stamped for another 180 days.

What am I missing?

Your issue is the current Cambodia Thailand Border status. Given that problem if only by land then Nong Khai and cross the border to Laos. Get bus or train or fly to Udon Thani.

In bangkok now that all the land borders with Cambodia are closed the closest land borders that are open for a land border bounce are the borders in Lao.

SWD Transport ( goes to the Savannakhet border and back every day

I believe they charge a premium for DTV people (to get you out/back in the same day)

Their schedule is on the weblink I jumped

To be completely honest, you probably could find a flight to KL and back the same day thru one of the budget carriers cheaper than you could border bounce by land with a service on a 20+ hour bus ride 🙂