Don't bother tears before bedtime unless you have buckets full of money ... like start with a million pounds and end up with 100,000 quid left in the pot before you scratch you're head and say I am fucked . Slow boat to blighty back .
So you are living on the east coast of Vietnam and you want to extend you're visa there. If so bangkok is ideal if you haven't been or if you have limited funds Vientiane would be the option ... penang is more comfortable but I think