Sure, they embed the documents on miniaturized gold fish and guppies..
Im sure there are microfish or SOME kind of records from 10 years back.
The term is microFICHE - there are no FISH swimming around the bank.
Banks do keep records on microFICHE, for 7 years, but once an account has been closed, they generally dump the records after 2 or 3.
"Knowledge is Power - use it as you see fit !
I am not a lawyer or a member of the legal profession. My advice is based on research and experience, my own and others, some who practice law. You decide for yourself what actions you do or do not take from my advice.