My xbox has freezing issues and I've tried sending it to mario and Gametech but they told me they can't repair it..any recommendation?

you may check to power stability, the Disc etc. (jack sparrow ver might cause that)

repair is always the last resort.

how do I check it?

Power--Try another power outlet.

Disc--Try change anotehr disc.

In short, whatever is external might cause the same problem. try to change them 1 by 1 see ifthe problem recurring. You need time for this.