The parties are free to agree with an arbitrator as to the consequences of his resignation as regards—
his entitlement (if any) to fees or expenses, ...
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
If or to the extent that there is no such agreement the following provisions apply.
Where an arbitrator resigns, a relevant person may (upon notice to the other relevant persons) apply to the court to make such order as it thinks fit with respect to the arbitrator's entitlement (if any) to fees or expenses or the repayment of any fees or expenses already paid.
For the purposes of subsection (3), each of the parties and the arbitrator is a "relevant person".
The leave of the court is required for any appeal from a decision of the court under this section.