What does “expected around ZAR 21,200,000” come from: completed sales, asking prices, or the developer’s figure? I would ask for comparable transactions with dates and enough detail to explain why they are relevant to this particular flat. Also ask how each agent would change the plan if buyer...
It would help if you clarified the fee structure: is it agreed for the whole scope or based on time spent? Also, what would the client actually receive at the end—a written report, recommendations, or another defined deliverable? “Energy assessment” can mean different things to different owners.
Diego's distinction is important, but I would go further and split maintenance into cosmetic work, known functional repairs and uncertain defects. Buyers may negotiate the first two because they can estimate them. The third category can stop a deal, especially if the buyer's financing leaves...
I would separate visible, costable work from open-ended problems. If the work can be itemised, a buyer has something concrete to put into a lower offer. If its extent is uncertain, walking away becomes much more attractive when there are alternatives. Seller motivation matters too: 109 days...