Fan timer (bathroom)

Hi there

My builder recently fitted an Xpelair timer fan in my bathroom. However I don't know how to set the timer. Also, the fan stops running after a few minutes even though the light switch is still on. Can anyone assist?

Regards

Sounds like he hasn't connected it properly.
The fan is usually supplied with a switched live and a permanent live.
When the supply via the switched live is present, the fan should run continuosly and when this is removed i.e. light is switched off, the permanent live is used to feed it untill the timer expires.

p.s. is he registered? did he issue certification? if not contact trading standards, he's in breach of building regulations.