WOOO found out what it is! The wires from the speaker to its built-on connecter were the wrong way around, fscking factory workers playing me about.

The door panel has been off about 9 times in the last 3 days, this is probably done now :)

it's the standard head unit, just slots straight in. Infact i have a new standard head unit because the vauxhall dealer gave me the wrong security code, so he just shoved another one in; same problem.

Any more ideas?

check the connections that are going into the headunit, its worth double checking everything.

I put some infinity speakers in my front doors, everything seemed fine, now my left speaker fuzzes/squeeks a bit and sometimes just doesn't work, it's definitley not the speaker because we got a replacement and the same thing happened with the new one, the old standard speakers don't have this problem. the connections are very tight and haven't come loose, no wires are touching or are very close to each other, i don't have a clue what could be wrong.

Does anyone have any idea? It's only the left speaker, the right speaker is perfect.

Thanks