Did your lease have a break clause?
If so, then my recent experience with a lease break fee may be useful.
I am a landlord and in my case there was provision in the lease for a break fee to be paid by the tenant if he breaks the lease before expiry. But not all leases include this clause.
Getting the fee out of the tenant required a hearing at NCAT.
After being paid the exact sum I emailed the tenant that the money (I spelled out the amount) was received.
Regardless of whether there was or there was no break fee in your lease it is only proper that whoever receives money from you must offer a receipt of some kind. Even a simple email like I did is good enough.
Also, if your lease had a break fee clause you need NOT pay rent until the end of the lease. The break fee is to be paid when you vacate the premises. If say you vacated on 1st of the month and paid rent until the 15th, then you should reduced the break fee paid by 2 weeks, because you have overpaid the rent.