I have just noticed that my left headlight is significantly dimmer than the right. I changed the bulb but there was no difference. The left indicator works OK with no headlights......Now when I turn on the lights, the left indicator will not work. Also, the left main beam will not work although the bulb looks OK.......No other lights are affected.....Summarising, left headlight is inferior, left indicator occasionally works and left main beam does not work. Does anybody have any idea what may cause all these problems to occur at the same time?

Its either going to be a loose or erroded connection:
Disconnect the lights, clean the connections, reconnect and see if it solved.

or

A bad earth, sometimes the earths come loose.
Locate the earth, disconnect it, sand down the connecting point and reconnect.

It may be something else entirely but thats what I think anyways.

Which Punto is it?

Fiat Punto 1.2 16V HLX Y Reg

I'm thinking earth connection because when I turn the lights on, the radio has huge interference on Medium wave.