Bond account has summons since 2010

We are in the process of selling our house and have been told by the conveyancers that there is a summons/interdict on our bond. This was done in 2010 we have been told by conveyancers that it will cost us +-10k for them to remove it. This is madness why is this on our bond and 12 years later why hasn't it been removed. This is absolutely alarming I am so disappointed in nedbank