Chronic severe sinus congestion?

There are two types of sinusitis:
Acute sinutitis is when symptoms are present for 4 weeks or less. It is caused by bacteria growing in the sinuses.
Chronic sinusitis is when swelling and inflammation of the sinuses are present for longer than 3 months. It may be caused by bacteria or a fungus.

There is one way:

"In cases resistant to treatment or medication, endoscopic sinus surgery might be an option. For this procedure, the doctor uses a thin, flexible tube with an attached light (endoscope) to explore your sinus passages.
Depending on the source of obstruction, the doctor might use various instruments to remove tissue or shave away a polyp that's causing nasal blockage. Enlarging a narrow sinus opening also may be an option to promote drainage."

Source: https://www.drugs.com/mcd/chronic-sinusitis