It’s not like it was defective out of the box... you’ve been using it for 3 years. Paying shipping for a free repair is totally reasonable. It is you sir who are being unreasonable.
Edit: and why do you note the amount of time it took him to respond? All were next-day at worst, and there’s a huge time difference between you. Oh, you expect him to sit there online 24 hours a day waiting for your email? Got it.