If we own a building together which had an overdraft put on an account for which I do not have right to signature and the ex-husband did not pay his overdraft can the bank seize this property and sell it for his debt…while I am legal co-owner?
They can indeed.
If there is for example still R 1 million outstanding on the bond and they only get R 500k for the house they can sue you as well as your husband for the shortfall.
All your other assets could also be at risk if they fail to get the amounts owed from your husband. My best advice would be that you and your ex-husband come together on this and consider a plan to get rid of the house. The best would have been to sell the house the moment you divorced. You need to sit around a table and come to an agreement as to what to do with the property.
You can also apply for debt review, but both you and your ex-husband would have to apply together.