Hi, thank you for contacting JustAnswer.com. My name is***** will do my best to provide the right answer to your question.
I'm sorry to hear that you are having a problem. What service are you a past customer with, or what website?
(You may not be eligible for a free trial, if you are a previous customer. I don't know that yet, since I don't know what service or website you are asking about. But it is possible.)
If you registered with the web site or service before using your current email address, it is of course there already, in the site's records, and you cannot re-register using it.
I suggest either contacting Customer Support at (whatever website or service) and asking about the situation, or just Reply To Expert (me) and let me know what website or service it is, and I will advise you more specifically.