How can I obtain proof of pension payments to satisfy Thai immigration requirements?

My pension is paid from the UK into my Kasikorn bank account but does not show up as a foreign transaction. Kasikorn advise me that to get proof of such I need a credit advice. If I want this to cover the last 12 months (to satisfy immigration) I must arrange it with the credit adviser in my local branch.

The process will take "around" 5 working days and cost 500 baht. I am not sure whether this is instead of or in addition to the 100 baht letter I have been getting every year up to now. Passport and bank book needed to get credit advice.

Wish me luck!