Welcome to our Community and thanks so much for your first ever post.
Just to confirm, yes - some accounts do require a deposit when joining us. This is separate from any install or activation fee and is held on your account until you leave us.
This is usually refunded back to you when you leave via a cheque refund. This is usually done within around 35 days of you leaving us and we advise to allow 10 days for delivery.
From locating your account from your forum information I can see that you have since been in touch with us and we have advised you accordingly about your deposit; I do hope that you are happy with what we have advised but of course if you need further assistance, please do not hesitate to get back in touch and we'll be more than happy to help you out.