Dishonest and refuse to pay refunds

I had my engine replace with them, they did a satisfactory job. But over charge me and when my broker brought to my attention, Garreth was going to do the refund. Three weeks later no refund. I've been calling he reckon he is not allowed to speak to me. Called the branch and requested to speak to the owner - Amanda reckon Garreth the owner is not available. When I question they put me on hold