Bond account details changed without any documentation

My husband and I have a home load with ABSA and have had for years. The bond account is linked to my internet banking profile so I am able to transfer extra funds into the bond account when we have extra funds. I can pay the extra money out as I need to. Today I could not, after phoning 3 different departments it was found that I am no longer the other person on my joint home loan with my husband and that his sister is. They refuse to give me any details on the bond account so my husband had to go to a branch only to be told we need to get copies of our bond contract to prove that myself and him own the property. We also then realised that this must have happened when his sister and him app**** for a totally different home loan for their mother's new house. That bond was not accepted so no contracts were entered into to. Now we have no idea how long this is going to take to fix, and we have to run from person to person and waste our time because ABSA somehow changed the owners of a property without any documentation whatsoever and I can't use any of MY money that I saved until this has been sorted out. Surely someone is responsible for this mistake and they should fix it and not me!! How could this be allowed to happen?