Key won't turn merc CLK

[oilandwater]

Hi, I have a 2000 Mercedes CLK and my key won't turn in the ignition. A common fault I believe. I could just have the main dealer come and collect it charge the earth and fix it, but I've heard money circa £2.5k being mentioned if it's the ECU.
I only paid £2k for the car last year.
Sooo, I have tried all the obvious, key batteries, main battery.
Anyone know of a good reliable diagnostic Merc work shop in the Cheshire/Staffordshire area.
Help.

[74merc]

Have you tried both keys? If so, it could be the ignition switch, in which case it would be several hundred quid. Have a look on mbclub.co.uk where you will find more info.

[oilandwater]

74merc said:

Have you tried both keys? If so, it could be the ignition switch, in which case it would be several hundred quid. Have a look on mbclub.co.uk where you will find more info.

Thank you.