There is a number that you can call for One-2-Call and request an increase of time, the cost being 30 baht for 30 days if my memory serves me correctly.

I've tried to find the number on their website to no avail.

Can anyone help me please?

Can't help you with a specific number for what you want to do.

However whenever I need to contact AIS for anything, I call their service center 1175.

Press whatever option they give me for an English speaking assistant, (think it's either 0 or 1…).

Have so far always ended up with courteous and helpful assistants.

As an alternative, if you know someone who has enough validity, you can transfer some of it thru their Web Interface

https://12calleservice.ais.co.th/EPPWeb/index.html

Sometimes much better than fighting to get someone who knows about it

- Martin

In this thread jay1980 said he called 1175, where they deducted 30 baht for each additional 30 days of validity.

In addition you should ask about any usage requirements as most plans have a requirement that you top-up or make/receive a call at least once in 90 days.

You can easy change it to one year, no problem. At the AIS office in Chiang Mai they are very helpful and professional (not to compare with the stupid ducks at some internet provider offices/helpdesks!)

I did not have to pay anything for it and it was done in 3 minutes.

The original poster is referring to Mao Mao 30 baht. It is a one-time charge of 30 baht, and for that, you get:

- free local calls 30 minutes within 5 days

- extension of validity 30 days.

You get it by dialing *500*9#