Ignition barrel fault

[Jakeconstable93]

Hi all 

2009 Audi a3 

recently had the dreaded ignition barrel failure, key would go in but wouldn’t turn at all. 
 

I replaced it with a new (aftermarket) one from eBay thinking this would be ok, this was an entirely new barrel with a new key, however now the car will start but instantly cuts out. 
 

Has anyone dealt with this personally and what are my options? Its a run around and I have no money so the cheapest fix is my main priority as I need my car for work, any help be much appreciated I’m rubbish with this stuff