Tutors can definately help provided the one you get is one you can work well with. Sometimes it helps to have the information explained to you by someone else in a different way. Also, some tutors can give you short-cuts and tips! I ended up getting a tutor for year 12 Maths (I didn't really need one but I'm pedantic about my marks), the guy we got in was a couple of years older and had done
really well in Maths (and all his other subjects) while he was in highschool. Tutors can definately help!
Even a study group with these friends that are also taking the class might help but I don't suggest using them as "tutors" as they are likely to get grumpy about it if you keep doing it. But don't be afraid to quickly ask someone something.
Also, don't be afraid to go to the teacher after class and say that you didn't quite understand something, many teachers (provided you're not a brat) will be quite happy to quickly go over everything again or organise a later time to go over everything. This also helps because you can watch them re-do it and often pin-point the exact element you don't get and then get them to explain it to you.
Other than that, I'd suggest writing down little summary sheets of every topic you cover in Maths, they will help you remember. Plus, they'll be in your own words and they're a form of studying to understand in themselves
If all else fails, sit your parents down and talk to them (again?), explain to them that you're not doing well, show them your tests with your marks and tell them that you don't want it affecting your credit and you want to drop to a lower Maths.
Good luck!