You are in need of a good radio LAME. Not one who woeld make faxes or phone calls to get the job done - one who has the knowledge and experience to fix your problems.
If the problem is as bad as you say, then you should get it fixed before further flight.
Got a scanner? Try it in your aircraft and see whether it's effected with the aircraft power on and off to eliminate local interferance or aircraft problems. If the problem is in your aircraft it's time to get a radio LAME. Carrying out fault finding yourself constitutes a maintenance task, and will require an appropriately licensed engineer.
