Singer CG 550 Top thread keeps wraping around the bobbin and jam

Have you checked the top thread is correctly placed in the spring of the bobbin case?

Also check that the bobbin being used is for drop in bobbin machines (class 66). They are designed to have rounded sides allowing the top thread to slide over them once the hook releases it. I was switching from a Kenmore with a front loading bobbin & found that regular flat bobbins are too tall so when the hook releases the top thread instead of sliding over the bobbin, it gets wound around it.
Hope this is useful.

Re-thread! Raise presser foot up before you thread needle eye. If presser foot is sitting flat against plate when you thread, the thread cannot locate tension disks, and that means all the dial-turning and fiddling with tension control won't do one thing to change tension. Why? Tension disks can't open to allow thread to position. You can rest assured you'll be smiling and sewing in no time. Just remember to put in new needle, pushing all the up into the needle bar before tightening the needle clamp screw, and raise your presser foot BEFORE you thread your new needle (make sure, too, that needle size compatible with weight of your fabric). Hope this helps! I have over 30 years experience, and many times a solution is easy as pie if you don't panic and take a moment to take a deep breadth and know many here are ready to help you out!
Jimmy