I have commented to your questions below. Also here are my thoughts...
I would like for you to get a second opinion on the need to place those cables from a totally separate company (not linked to Thyssen Krupp in any way). If they confirm that the cables need to be replaced then we will need a quoted price for them to replace the cables. I would expect that the cables are common to more than only Thyssen elevators so we should be able to go external to Thyssen to get this work performed if it is confirmed that it is needed.
Also we will need Knight Frank to double check the records to see if there was ever any mention of the cables needing to be replaced during the previous contract period with Thyssen Krupp. Under the previous contract parts were included at no cost to BAP but as soon as that ended then they immediately said that those cables need to be replaced. If there was never any mention of the need to replace the cables while under parts contract then we need KF to write a letter the head office in Thailand (someone at a very high level within the company) to ask them to explain this to us. Why there was no problem for 7 years and then suddenly the very first month that we didn't have the parts contract that suddenly those parts need to be replaced. We need to escalate this to the head office and ask them to investigate.
All of this said, we need to start to look at options to separate ourselves from this company all together. We need KFs experience and feedback on this. What is the best brand of elevator from a cost and service standpoint in Phuket? Get a price quote to replace them. How much will it cost to change one or all of our elevators? If we just cancel the contract with Thyssen then I expect that they will refuse again to sell us any replacement parts in the future. But it's worth a try and if they do respond like that then we escalate this to the head corporate office if needed.