In fairness, the retailer isn't making an illegal statement when saying that, and not overriding your statutory rights (which can't be overridden anyways).
This is the specific distinction (my bolding):
Originally Posted by foggy_lad
If you brought an item to this retailer which was faulty through defect etc then the retailer are obliged to deal with you and repair replace or refund, and should not be charging for repairs covered by your statutory rights.
The retailer is permitted to determine the cause of the fault, and whether that fault is covered under warranty or not. If it's not under warranty, then they are perfectly within their
rights to charge for that time in determining that cause. If the cause is found to be a warranty fix, then the customer is perfectly entitled under their
rights to seek a refund of any "examination" money paid.
Samebutdifferent: Lots of people put their car in for the NCT, to see if
theres a problem, but they pay for the NCT regardless of the outcome, even if the car is under warranty or not.