Ask the student to check any contract wording and relevant policy wording in the matter that should be available (although possibly buried) on the university's intranet sites. In many cases there will be details of how to escalate contact, timescales, and so on.
Collect all messages and correspondence together in a file, whether this is within an email account or otherwise. It takes a bit of time but it is useful to refer to dates where X was said, and it will show you how long, realistically, this has been unresolved, which your DC may also need or want to refer to, in case of things not going in the right direction.
Recommend that the DC approaches the Student Union for advice. There are usually parts of it or connected services that will advise on things that are not going according to expectations, and in cases of accommodation, certainly legal and tenancy support that will be familiar with how things work locally.
Get cracking on this. I do agree that the Winter break and the start of term will have meant that things have got delayed on the administrative side, but showing that you are not jogging along with the 'woolliness' may be quite meaningful.
It's not always wrong for the parent to attempt to engage, but it probably won't count for a lot if the matter is not an emergency. Most universities should be hot on GDPR and information restricting to protect students - a number of them do rely on this, as it's not only parents or people with good intentions that may be keen to know their business.