Common property permanently located on owner’s lot

According to the strata plan and the terrace of my garden apartment is 100% on my title.  However, a raised and fenced platform on the terrace houses the hot water system (HWS) and meters for the whole block of 10 apartments. This takes up 3.2 sq m of my terrace. The HWS was there when i purchased but I did not realise this until afterwards. The fences need replacing and the EC has determined that the cost should be split 50/50 between the OC and me.  Clearly this is unacceptable as the HWS is illegally on my lot. I want to resolve this situation by either removing the HWS from my lot (likely to be too expensive to be reasonable) or re-drawing the boundaries with reasonable comensation to me as I paid for this area when I purchased the apartment.  Verbal advice from the Offfice of Fair Trading is that the HWS must be placed on common property. I now intend to write to the OC seeking resolution of this issue but I am not sure what to put in the letter so that they take it seriously and take action within a reasonable timeframe. Any suggestions about this or my rights and responsibilities in this situation?