Cat converter 156

[Romeo156]

its expensive to get a genuine cat converter; is it quite good to get an after market ones? anyone selling second hand i would be intersted and Is this a common fault with 156? I also rang up liverpool exhaust claiming they can repair the cat converter. I dont know what to do please help.. the dash lights up saying motor system failure got to dealer. too k it to alfa and they ssaid that its the cat converter honeycombe has failed need replacing and possible damage to o2 sensor...