How to handle refunds

Hello,
I'm new to Homebank and I can't seem to find how to handle correctly refunds.

Let's say I payed a doctor 30 euros. I create a transaction in a debit category "Doctor".
Then the state refunds me 20 euros. If I create a transaction in a credit category "State refunds", Homebank won't guess the link between these two transactions.

When I will ask the software "How much did I spend last month in medicine ?", it will respond "30 euros" and not take into account the fact that I was refunded of 20 euros.
The problem persists if I create a transaction of positive value in the debit category "Doctor". The sum will be 10 euros but the total spent displayed will still be 30 euros.

Thus my question : How can I handle refunds with Homebank ?
I would like the software to tell me I spent 10 euros in medicine last month, but still be able to know that the real cost was 30 euros and that I was refunded 20 euros.

I'd be very glad if you could help me.

Thank you
Olivier