[charlie 22]

Hi all, got bad news today my car went in for its mot and an oil service plus a couple of other job. My mechanic rang me to say the car failed on a number of things the most shocking was the co2 emissions. He had to put in two bottles of cat clean to get it to pass the test and it did just about. He said that it might not pass next time. It is an after market stainless system so do I go back to company I bought it from for there advice, but as it has been 2 years not sure what advice they could give. Plus I have had the car remapped so my gut is saying that it might be the cause of the issue because when I got it done the guy said the fuelling was to rich at the top end so brought it back down BUT I did find I could smell it being really rich on start up when I was using premium fuel so could that have an effect on the cat, but now start to us regular and the smell is much less . I also average 3 hours of driving a day mostly at motorway speeds so the cat gets nice and hot. Where do I go from here?
Many thanks Chris.