write letter oso no use, you'll get it's management decision
if you fully met the requirements, write a letter to appeal, but not guarantee will be successful

how about your total credit exposure? meaning total credit limits from all your active cards, housing loan, hire purchase. If it's very high, some banks don't like it. And also some banks don't like to approve new customers with high outstanding balance in other cards.

As for the letter, just google letter of appeal and modify accordingly, just a simple one or two lines letter will do

that's strange, since you've submitted all your income documents, actually no need to submit ur cc
so, try to fax or mail your appeal letter and see how