Toolbox Appliance Repair

I approved a $550 Visa payment on Dec. 20, 2018 for 50% cost of display unit which I was assured would fix our range. A couple of days later the technician replaced unit and advised me he was unable to fix our range and that we would receive a full refund for the display unit which he took with him. I have called Roger several times and to date have not received the reimbursement he owes us. Update - after 3 weeks of Roger advising me my reimbursement was coming, he now advises part is non returnable so I'm out my $550! Concurrently he mentioned my poor review of them on Homestars.