You are a customer so you can insist on certain documents. Or you could move the money to another bank that gives a physical letter and attach copies of the transfer of funds along with LoE. I would always bank with a bank that gives me physical copies of whatever I need as long as I am under immigration control.
Thank you very much for your information. My concern is that letter which should be printed on the bank letterhead paper. I can get the profolio, but the front desk refuse to write me a physical letter which made me very mad. I was thinking to fight with them.