Horrible bullying from ABSA - no fault of ours.

We had the misfortune to sign, in all good faith, an agreement of sale to buy a flat, signed by the person we assumed to be the owner. This flat was, unbeknownst to us, subject to a distressed sale by ABSA bank. It took 3 months for the bank to agree to sell the flat - luckily we did not end up homeless in the meantime! The bank then instructed Hammond Pole attorneys to process the transfer. We feel bul**** and harassed by these attorneys. There is a clause in the agreement of sale that we would be given vacant possession of the flat on transfer. Hammond Pole now insist we go ahead with the transfer and "We can also not guarantee vacant occupation as the property is still owned by the current owner. The seller did sign that they will vacate the property on transfer (Clause 5.1 of the Offer to Purchase), but unfortunately we do not have control over that". Surely, if ABSA has taken over the sale, we should have been asked to sign a new agreement of sale with the bank; and how can they subsequently insist on transfer but abrogate responsibility for a clause in the original agreement of sale. I am truly horrified with ABSA's bullying of an entirely innocent party. I would appreciate a call from them to explain their justification for insisting that they are not responsible for making us take transfer of a property that we cannot use. Disgusting.