Issue after settlement – vendor not responding

Hi guys, we recently moved to Perth from Brisbane – we bought a house and settled on it on the 10th of January.

The house came with a CCTV system and the vendor told us to contact the security company to register the device in our phone and get the CCTV working. After we moved in, we rang the security company and they came and had a look, confirmed that the device has to be unbinded first before registering our mobile. The number is apparently the vendor’s EX and they went through a nasty divorce. But she did not disclose any of this information prior to settlement. When I contacted her, she have me her EX number and his lawyer and asked me to deal with him directly, I did contact him but he is finger pointing at her, and it got into a she said he said thing. I am stuck not being able to use the system, and I am worried about the serious breach of privacy – I contacted my settlement agent and their suggestion was to go to small claim court. The cost to replace the system is about 5K, and I even offered the vendor I could put in 50% and she can put in the half and we can reach an agreement. Again no response for that also. She thinks its not her responsibility to sort it out, the real estate agent is not willing to help either, she has told him not to contact her on this matter. We bought this interstate with good faith on her but I am not sure what else I can do.  Any ideas? Thoughts?