How to override the thermostat on my Ariston boiler

[gauntla]

Please can someonwe tell me how to override the thermostat on my Ariston boiler. What is a receiver unit and where is this illusive override switch. I'm freezing. Called two gas fitters who are too busy to come out but left me instructions I don't understand

 

[Apache]

The receiver looks like this

http://www.ariston.co.uk/products/gas-boilers/controls-wireless/signal-receiver/0000000017/

Are you sure the boiler is lit?

Are you getting an error message?

Do you have any hot water?

What is the exact model of boiler and thermostat?