New Branding and Signage (Gone Wrong)

We have just moved into new offices which our 2 companies share, one being wallpaper and one a security service provider. We decided to use Carbon Digital owned by Eddie Van Z****en to do all the new contravision and signage as he has done most of the tenants in the building, thinking he is good! Big mistake, we should of stuck with our original signage guys!!! We met with Eddie, explained what we wanted and left him to come up with proofs of the designs. They couldn't get it right, lots of back and forth with a million and one excuses why it cannot be done, or why they cant install etc. We then raise the issues with Eddie about the faulty workmanship and peeling off the windows 1 week after being installed) the different shading on the backgrounds etc. They installed onto dirty windows trapping the dirt which is visible on the inside of the offices. We then send an email requesting a full refund due to them not able to fulfill and meet their obligations, and we get a reply telling us we are ******, we use foul language and every other excuse to avoid refunding us, plus he then sends us his terms and conditions on the day we ask for a refund. This guy is a great manipulator, promises you everything but turns up short on the delivery. Don't use these guys we paid our school fees.