Pending Cancellation of Bond since December 2016!!!!

I cancelled my bond in December 2016 and it was quiet for the whole year, until this year when I was threatened with a lawsuit and repossession of my house because I "apparently" did not cancel the bond. They can see the cancellation amount on record and they are now telling me that they had no record of a cancellation letter/form, that I still have a copy of, which was completed at the FNB branch in Hillcrest, KZN. I have called and spoken to a number of people and the most frustrating this is that I have had to explain myself to over 10 people because each time I get to the branch, I am told to call the Home loans division where I have to explain myself again. this is really frustrating and I am at my wits end now. I finished paying off the bond in 2016, but almost 2 years later I am still trying to cancel. I think FNB should change their motto from "How can we help you" to "How can we ***** you over once you are done paying us back". Seriously!!!!! ☹