I may be wrong but as far as I'm aware, an owner can change the element themselves if they wish. I recommend they call an electrician to do so when I receive inquiries about this, purely because of the risk that someone will do it wrong and electrocute themselves or short something out.
Quite right. Under ECP 51 the owner/occupier is allowed to do this. See also following from Electrical Safety Regulations 2010:
64 Exemption for domestic electrical wiring work(1) A person who carries out prescribed electrical work in reliance on the exemption in section 79 of the Act (exemption for domestic electrical wiring) must carry it out, and test the work, in accordance with ECP 51.
(2) For the purposes of section 79(1)(a) of the Act, the domestic electrical wiring work that an owner of premises may do is as follows:
(a) work on a domestic installation that has a maximum demand at or below 80 amperes single phase, or 50 amperes per phase in multi-phase, and is within the work described in any of paragraphs (b) to (f):
(b) installing, extending, and altering subcircuits (including submains), but only if—
(i) the person does not enter (whether directly, or by holding any material or equipment, or otherwise) any enclosure where live conductors are likely to be present; and
(ii) the work is tested and certified in accordance with Part 2 of AS/NZS 3000, before being connected to a power supply, by a person authorised to inspect mains work:
(c) removing and replacing any of the following kinds of fittings, but only if the work does not involve work on any switchboard:
(i) switches, socket-outlets, and light fittings:
(ii) permanent connection units, ceiling roses, cord-grip lampholders, and flexible cords connected to any of them:
(iii) batten holders:
(iv) water heater switches:
(v) thermostats:
(vi) elements:
(d) removing and replacing fuse links:
(e) connecting and disconnecting fixed-wired appliances:
(f) relocating existing switches, socket-outlets, and lighting outlets that are supplied with electricity by tough plastic-sheathed cables