Never sign a sole mandate with this Estate Agent

I was convinced by the agent representing Wanda Bollo that by signing a sole mandate I would receive far superior service as opposed to signing a multi agent mandate. This was so untrue. No effort has been made to sell my house. No contact since June 2017 to have a show day- they are supposed to arrange in accordance with their mandate a show house once a month. They purposely block other estate agents from showing your house to their potential buyers as they do not want to share commission. My request because of this breach of contract that the mandate been cancelled has been refused by the extremely volatile and rude Wanda Bollo herself . She refuses to cancel the sole mandate but also stated they will not do any proactive selling of my house or show days. She also personally insulted me and quite frankly was totally out of control.