VOSA/DVSA won't be interested due to the length of time between the test and rexamination , however I would at first ask the garage who conducted the test to explain the condition of the vehicle and go from there . It may be worth speaking to the local Vehicle Inspector on the area and advising him of a potential risk from the garage although VOSA/DVSA are very short on staff at the moment and it is increasingly rare they are seen out and about . It is good practice to advise on items that may not be testable and are at fault or items that are outside of for example prescribed areas , however this has clearly not been done .
There are also considerations as to where the corrosion is and whether it is within prescribed areas such as steering , suspension , bodymounts , and seat belt mountings .
MOT standard is say 3 out of 10 , Service standard is 8 out of 10 so a big variance there , it would be interesting to see some photo's of the corrosion however .
You could have a car such as a Nissan Almera with a completely rotten front crossmember underneath the engine mounting (engine mounts are now testable) , the new item of engine mounts doesn't include a prescribed area , nuts really .