Can lodge an objection if I think my filing was incorrect?

What do you think you have done incorrectly? You can click on the "request correction" on eFiling and resubmit your return.

I think I put the amount for medical aid additional expenses by the wrong code.

Are you referring to the medical expenses not recovered by medical aid or amounts on your IRP5?

Source code 4020

Source Code 4020 is for other medical expenditures not covered by your medical aid, are these the expenses you wish to add into the return?

I did add it but according to a colleague of mine the amount must be indicated by another source code as well ...My medical expenses according to my tax certificate was R 6706 but I only received R400 back were as I received about -R 2000 back from SARS if my expenses are so much.

For out of pocket expenses that is the correct source code. The reason for your small refund is because of a complicated formula SARS uses for this calculation - Tax deductions for Out of Pocket expenses