Alternator

hi, 

I’m just wanting to know if anyone knows whether a delco alternator is suitable for my 2013 A4? I’ve had one fitted under a car care plan exactly a year ago and it’s faulty. I took it to a local mechanic and he said that it isn’t the right part for my car and he wouldn’t use that model. I’ve been trying to fire it back to the place that fitted the delco alternator to see if would replace it under a part warranty because I believe they have 18months warranty on it but they keep dismissing it and saying it’s my problem and they won’t budge. If I can prove that this isn’t a genuine part then I have a chance at getting them to replace it. Any answer appreciated. Thanks.