Well heres the story.. looking for a little info :

Bought MK4 Golf 1.6SE for £1500 from a garage....
with 3 month warranty although garage will not honour this and courts taking forever, so i would like to know what you guys think may be the issue please:

Failed MOT before purchase at 3.6 Co2
Garage put new cat and air flow mass sensor on and 'suddenly' they got it passed at 0.00 Co2 strange

Well took it to my local when I picked it up just for a check over and they told me that there is some serious smoke coming out of the exhaust (where i live the car is never in traffic to see this, neither did i pay much attention when purchasing.. yes my own fault.. ) And also they informed me that number 1 spark plug was fouled with oil....

Next thing i done was get a compression test readings as follows:

Cylinder 1 Cylinder 2 Cylinder 3 Cylinder 4
90 90 110 100


Does the above have a meaning to you guys?

The third and final thing i done was took it to an MOT station just for an emmisions test, and it shown 1.7 in Co2 and a silly level of hydrocarbon right before the MOT testing machine shut off due to the little bottle in it and pipes becoming full of water....

Oil is fine and there is no oil in the water, and i done 300miles in that time, i am in no way a racer, it was a new and expensive car to me so just kept it all low not to ruin it...

What do you guys think the issue may be?
Would you think the MOT pass on it was a little dodgy or not?

Any info/advice would be greatly appreciated as i do not think the garage cares that i have put court proceedings in place, so i want to know what the above may mean, and a rough cost.

Thankyou very much in advance