Unfinished and shabby work

On 24 October I signed a quotation from Aqua Roofing and Construction for some demolition and building work on my property. They commenced work at the beginning of November on what, I was told, would be a three week job. By 1 December they had still not finished, and the following week they started reducing staff on site with still quite a lot of work to be done. The week of 11-15 December they only came on the Wednesday, and they haven't been back since. I have tried numerous times to contact the owner, Mike Spiro, but he does not answer my calls and he does not respond to my messages. I would advise anyone contemplating using this company to steer clear of them - besides them not finishing my job, their workmanship is shabby and their supervision almost non-existent; my entrance door would have been put in upside down if I was not on site when it was installed.