To me the
IAP chart looks even more confusing than Duke of B suggests.
Two racetrack shapes are depicted at the FV. The northern end 180 degree turn is common, but two southern ends are depicted. Inside the shorter racetrack shape, it says "MNM ALT 4000". South of that, outside the shorter shape but inside the longer one it says "MNM ALT 2800" and "IAS MAX 220 kt". Outside the longer shape it says "HIPODROMO Cat A&B 3 min, Cat C&D 2 min".
Presumably the shorter racetrack shape is the holding pattern, and the longer one is the racetrack course reversal itself, as labeled by HIPODROMO.
My interpretation would be that the MNM ALT 4000 refers
only to the holding pattern, and the MNM ALT 2800 refers to the racetrack course reversal that is the first part of the IAP. If not, why is the MNM ALT 2800 there at all? It's not unusual to have a higher minimum holding altitude than minimum altitude for commencing the approach. That's how I would expect it to be depicted.
I suggest that you not only remind pilots to maintain 4000 ft where required, but also encourage your AIS charting section to add a note to the effect that the minimum altitude for commencing the procedure is 4000 ft until reaching the IAF at the FV.