Managing difficult owners

In my complex, there is one owner who continually complains about the Strata Managers, extended times to have repairs done etc. All efforts are made by the EC to communicate immediately with our Strata Managers, who are very responsive to our requests for repairs, quotes etc. Earlier this year, this owner informed the Strata Managers that there was a long-standing issue with a blocked toilet in his townhouse (1st notification). The Strata Managers worked to arrange tradespeople to attend to rectify the plumbing issue ASAP. In short, the tradespeople were refused entry, with the owners saying they now didn’t want to bother having the problem fixed. The EC asked for a letter to be drawn up, outlining that as the owners had refused access to 2 plumbers, that a cap of costs amounting to the original quote of $5K would be placed on any future repairs, in the event that refusal to complete the work resulted in more major (and expensive) plumbing costs at at later stage. Adequate time for reply was allowed, however the owners never did agree to have their toilet fixed (??). Of course, 6 months later, there are now major plumbing issues in the building, affecting 3 townhouses, with the above owners also having more issues.

Can the EC enforce the conditions in the letter regarding capping costs, given that more than reasonable attempts were made in the first place to fix this issue, and it seems from today’s reports that refusing this initial work has resulted in much more extensive emergency plumbing work to be required, and had possibly affected the other units on the same line?