Don't threaten people

We took a home loan out in 1997 and rented out the property in year 2000, everything has been fine, we received and email on Friday 31/7/15 from Andre *** saying that we owed them just over R10,000 due to the bond being short paid as interest rates apparently went up in March, we are not aware of this as we live outside the country. I telephoned Andre, where we had a personality clash as he has an extremely bad attitude and threatened me several times! I asked him why someone in Durban was handling our Johannesburg account as I had always dealt with someone in Johannesburg, he said he is in charge and I was to deal with him! After a heated debate I got an 086 number for home loans, imagine my surprise when the department is called credit rehab! 12 telephone calls it took for me to finally speak to a supervisor as all the managers were out! We have not had a statement on this account even though we have asked numerous times! I am told we still owe nearly as much as we borrowed after paying all this time! I wonder if there is anybody at standard bank that can give me some answers!