Paying commission for bad attitude

I gave a mandate for the sale of my flat in Noordwyk, to Belynda Nauschutz, the principal at Midway Homes. The troubles started when she neglected to check the tenant's notice period and told the buyer that he would be able to take occupation while the tenant was still legally occupying the flat. She attempted to blame everyone, including me, and refused to take responsibility all while the buyer had to pay for storage and AirBnb for a whole month. I have never experienced such bad-to-zero communications. At the end, I can't believe that I'm paying her a substantial amount of commission to be dealing directly with the seller cause she is so unreliable.