MOT Advisories - Auris 2010

Hi All,

I had my MOT done and all passed, however I got a few advisories which I would like to know how serious they are and would it be expensive to get it done as per your experience. 

Monitor and repair if necessary (advisories):

• Rear Sub-frame corroded but not seriously weakened (5.3.3 (b) (i))  (I am told by the garage that this is not possible to be fixed as its the chassis) 
• Suspension arm corroded but not seriously weakened both front (5.3.3 (b) (i))
• Rear Brake pipe corroded, covered in grease or other material (1.1.11 (c))
• rear exhaust joint corroded

Do I need to worry about these? My previous MOT had no mention of any advisories.

Thanks in advance.