Where the regulator makes arrangements under section 225B, the regulator may by notice require the registered provider concerned to pay to the regulator—
"Relevant expenses" are—
Sums mentioned in subsection (1)(a) are payable at the end of the period of 28 days beginning with the day on which the notice is given.
Interest may be charged on any sums not paid by the end of the period mentioned in subsection (3) at such reasonable rate as the regulator may determine.