Hi Daniele
Post your request on the web forum Avcom.co.za you will get lots of good advise there. Basically the SAAF will not entertain any application without the prescribed maths and science, even with a comm. As for the major airlines they too will require decent maths and science symbols. My personal advise is to get extra help with maths and science until you are able to reach the required standard. Although one does not reallyneed any thing more than basic maths and science to fly, the airlines and airforces of the world use these as subjects to profile candidates as do many of the university gained professions.
Basically there are no short cuts. Get the help you need wrt maths and science you would be surprised what a good teacher can do to help. Most of the people who do badly in maths have poor teaching. Maths is not difficult if you understand the basics.