I have achilles tendonitis for several years and it wont get better?

Get examined: Pain in the back of the heel towards the back of the leg is where achilles tendonitis occurs, but are you sure that's what you are dealing with? Get examined properly. Xrays can infer position of soft tissue but mainly highlight bone. To examine the achilles, an MRI would be warranted to check for damage - even a longitudinal tear which can be very subtle but result in lingering pain.

That's a long time: I would be curious to kow your prior treatment if any. Proper treatment should not take that long to heal. See a doctor, or physical therapist and have your condition treated appropriately.

Other suggestions: I have been dealing with this condition myself for over five years, which was refractory to stretches, heel lifts, anti-inflammatories, and eccentric strengthening. Newer treatments including ultrasounded guided tenotomy & prp really helped me. People are also now using stem cell treatments.