W.P Roofing - No support

W.P Roofing has partly installed a new roof at our business, and waterproofed the rest of the roof. After the first rains everything seemed fine, however after some heavy rains over the past few days the roof is leaking way worst than before the waterproofing was done. We have been regularly phoning their office number, as well as the owner (Richard Davy) directly on his mobile phone, but no-one answers. They say they guarantee their work for 10 years, however it didnt even last a month. The inside damages to the laminated flooring will be substantial due to no support.