Eighteen months ago I purchased a single license, and now I would like to upgrade to a developer license. However, I can't upgrade via the form settings page because I used the single license to create a form for a client's website, and since the completion of the project they have deleted my user login (nice, I know, but it was a very security-conscious client who wanted all activity on the site to take place behind their firewall once it went live). Is there another way that I can upgrade?