I know this has been dealt with in another thread indirectly ( http://huahinforum.com/viewtopic.php?f= ... nd#p399506 ) but it may be more easily located as a direct thread. I followed cookie's advice today and extended my backup sim by four months and in the process put on 80 baht of credit. Much better than wasting 30 baht per month using the ussd code via the phone. This is a backup phone I rarely use but can be contacted on if for some reason the main one has gone flat and I have not noticed it so I do not carry a lot of credit on it.
I notice they now have two machines in MV at the AIS shop which certainly reduces the queuing time (not helped by people like me adding 20 baht a time to extend the expiry date).
To save people hunting for the tip it is just a matter of adding 20 baht credit using the machine outside the AIS shop in MV which not only adds the credit but also adds a month to the expiry date. As I said I added four months worth today and understand the maximum advance time you can get is a year but cannot be certain and am sure someone will correct this if it is wrong.