Thai Shares published an article a while back about Citibank increasing its minimum deposits. You can read it here:
Big Fee Increase From Citibank
The letters sent out to Citibank customers provided no specific details upon why it was necessary for the bank to increase its monthly fee by more than 65%, and the total relationship balance required to waive that fee by 900%.
Fish Tank, given the above mentioned increases, it is not surprising that you have decided to change banks.