Show me proof

Today i received an email from "SYMINGTON & DE KOK/S SLABBERT" in relation to a business account that you closed. I learned this when a customer needed to make a payment into the account. I contacted you to inquire on why the account was closed and i was never told it was due to the account fees that my startup couldn't afford at the time. Needless to say, i opened a business zero account and life carried on. The said email i received states that YOU have been trying to contact me for the years the account has been closed to no success, which i find strange considering that i personally bank with you and yes, my business zero account is still active to this day. This naturally means, you have all my contact details. So you can imagine the dismay when i saw the email pop-up in my inbox. With that being said, the "collections" email states that you will adjust my personal credit consumer profile. You will not be doing that, what you will do is write off whatever you say i owe because i have NO email, call or sms (as the email states) that came from of you of the fact. After all, its something i would've settled had i been contacted all those years ago. I WILL NOT BE BUL**** BY YOU. Failure to do so, will lead to a complaint being filled with the Ombudsman. I look forward to your response.