Dear David,
First of all I would like to apologize for the delay in writing this letter. I am confident that you are totally aware that when somebody is issued with their visa, then this is totally natural as first they will be shocked for the first month, and then they will rush into doing their packing and sorting out, and getting ready to move to their new house which will leave them no time even to think about themselves.
Secondly, let me hereby take this opportunity to appreciate you and Mr. Mahmmoudi for all you have done. … You were always there, answering, calming down , and enlightening my heart. Now, everything has finished and you have left with new comers. I am sure that you will handle their cases and get their visas as well, as you did once for me. Disappointed and desperate, I turned to you 2 years back. Almost everybody had told me it was impossible to get the visa for me with the conditions. Yet, you did your best, and truly, you did a great job. I would like to appreciate you once more for all things you have gone through.
Wish you a successful career ahead – like before.
Best Regards