Ok there are a number of competing issues here.
Btw I am NOT a lawyer but there is some pretty clear legal advice.
1. the landlord has a duty of care. Some of that duty of care is obvious (property needs a roof!) but some is less obvious. You might be able to argue that a duty of care the landlord has is ensure that the locks are "fit for purpose" and that if there are unknown numbers of copies of keys then I would argue that it's not fit for purpose. A letter from the police saying that the thief MAY have had a copy of the key may help your case here.
https://www.citizensadvice.org.uk/housi ... ibilities/
2. The landlord is NOT allowed to enter the home when it is rented out without the tenants permission. Anything that the contract says that contradicts this is not allowable by law.
https://www.propertyinvestmentproject.c ... -of-entry/
So you could easily argue that you can change the locks and that the landlord can't do anything about it as it does not affect the rights of that landlord i.e. they can't enter anyway without permission. They may argue that they want copies of the keys etc, an you should give landlord new copies, but they can't stop you changing them.
3. I would do this...
a) write to the landlord and cc in Trading Standards AND the local university student welfare.
b) explain that your daughter has been burgled and police believe that copies of the keys are in circulation
c) give the landlord 7 days to change the locks or explain you'll be changing them yourself
d) if the landlord says no explain that you'll be holding him/her liable for any further damage under his/her duty of care
e) speak to university and ask if they can help put pressure
hope this helps - sounds like a horrible situtation