I am selling my car and will have to answer calls.

I am selling my car and will have to answer calls. I am 22, male. I have severe generalized social phobia and a stutter. Talking on the phone, ordering or answering questions at the counter are my night mare. Please help becuase I am so afraid. I have to take benzos to even get out of the house basically. Severe stutter can be worse than many types of chronic illnesses (I have chronic pain, tinnitus and mental health and for me stutter is there with depression, but worse than anything for someone with severe SAD).