ForestofDoom
Discovery TD5
phone them up and tell them you think it has a dodgy MOT (relaxed as you called it) and tell them you are going to take iti too the vosa testing station you will be suprised how qiuck they react, i am under the impression car sales places cant do there own MOTs so you might find you have to ring the place that did the test as it will be them that will lose there licence
neil
Dont do the above
Ultimately you want them to volunteer to rectify it whether they are in the wrong or not and accusing them of foul play will only **** them off and make the distance to resolution longer and more complicated.
Be NICE!
At least in the first instance, and as someone else said, speak to the garage owner privately and respectfully.