Gutters and downpipes

I appointed Genesis Construction to install downpipes and gutters on my house. They asked me to pay upfront, which I did. I made the payment on 27 June and they have not come to install it yet. After a month of waiting, they offered me a 50% refund. I never received the refund. I followed up numerous times through phone calls and emails. Every time there was an excuse for why they have not come to install the downpipes and gutter yet. Eventually my phone number got blocked and I cannot get through to them anymore.