A couple of problems with selecting a sub-domain within WHMCS

I've got a couple of problems, and it would be good if I could get them sorted out over the weekend, as we go live on Monday.

The first problem is linked to a question I had on Monday. On Tuesday I received a reply asking me to give access to my admin, but since then it has been ignored, which does seem to be the way things are done these days once access is given.

https://premium.wpmudev.org/forums/topic/domain-to-use-not-asked-when-purchasing#post-833038

I found what I needed to do to give the user a choice of domains, but they are not linking to my Multisite. If I select a different domain than is the main one with the installation, it then changes it to that main domain, instead of using the selected sub-domain.

Also, when a domain is selected that has already been taken, it doesn't say something like:

Sorry, that domain has been taken. Please try another.

Instead it says:

The domain you entered is not valid. Enter only the part after the www. and include the TLD

That doesn't help in explaining the problem, but it also isn't correct as there would be no TLD to add for a sub-domain.

There is some great support on here at times and I try to give the benefit of the doubt, but please do not ask me a question on this and then ignore me, which has been the case for the past month. I now have only 2 days to do a lot of work on this, work which would have been done if tickets had been answered. I've heard the response that they are dealt with in the order they come in, so I've not asked what is happening on that ticket, but then that means you think you got away with it and just respond to those who make a fuss. if that is what is required, then I will make a fuss when not answered.