Am running openerp version 6.1.1 and sometimes customers give more money than the cost of the good been sold so that they can come and add it to it later to pick other goods in future. If they come and pick another good, It's all well but at times, they may come back to collect the extra money(deposit) paid earlier. I really don't know how to do this in openerp. So essentially:

How does one make part refund of a paid invoice which has excess?