Netflix complaint: Charged for two accounts

My wife has been telling me for a while that Netflix are charging me twice a month but I run my own business and have just not had time to check.
I finally got round to contacting Netflix. I was told I have had two Netflix accounts for nearly two years, the chap I spoke to informed me that one of the accounts had been created by mistake using my email address with one letter missing. He very quickly cancelled this account and refunded me £8.99, even though I have been paying double for nearly two years.
I believe Netflix would have known this email address did not exist and the account has been created by mistake but have continued to take the money.
I believe Netflix should refund the payments to this account. I will wait to see what happens before deciding if I want to continue with netflix
I do not believe a company the size of Netflix do not have a complaints procedure.