Rewiring a property is messy, disruptive work. It happens in two stages: first fix, when cables and wiring are installed, and second fix when everything is joined up or made 'live', when the front faces of sockets, switches and lights are fitted.
If the new conductors cannot be pulled through the old slightly smaller metal conduit, these pipes will have to be chased out and new conduits / cables be installed.
At the same time a new distribution board would be installed, a surface unit.
Before the final quote may be submitted, the colour and style of switch and plug must be chosen.
Here are some links to reputable switches and sockets (plugs). Please take into consideration that there are combinations of switches and sockets that have USB Ports and the New South African Socket.
Also, please establish if there will be any two way switching, and also if there will be dimmers and LED lighting.