well it depends how nice your landlord are.
similar situation happened to me over a week ago.
i live in a rented flat where i have a prepaid electricity meter. i top up twice a week, but because i was moving out soon i only need about �5 elect worth to last me for 7 days. but the company where i top up my elec says the min i can top up is �10. so i ask them, if i top up �10 and have money left over on the day i move out do i get to claim the remaining back, they say no.
they told me to speak to the landlord whether they can refund me. so i phoned up the landlord (hunters agencey) and ask for sme advice, i asked whether they can refund me the remaining and they can always claim it bk for the next tenant, they say NO, and that they dont get involved that side of it. so basically its the tenants problem. so i moved out with �6 left for the next tenant. i cant beleive that. i will never use Hunters EVER again.