Apology Letter to a recruiter ?

I encountered a strange situation today,
I was talking to a recruiter who was returning my call for employment opportunities. and I was just emphasizing my point just once during the whole conversation and he said I was "Cutting him Off" and hang up the phone on me.
I wasn't rude to him. I just want to keep in touch with this person not only because I know he was in a stress situation and he reacted in that manner, ALSO because he has good network so I dont want to lose his contact.

Could anyone please tell me how to formulate a formal letter in this situation conveying 1)thank you for talking inspite of busy schedule.
2) apologize ( Imight have bugged him maybe because I was anxious)
3) ask for some reference and leads with regards to my resume/qualification.

Thanks