JNT Damaged my Vehicle & Refuse to Pay for Repairs

JnT Egineering was hired by my next door neighbour to install a new solar geyser on her roof as her previous one packed up. During the removal of the old one, the JnT employee dropped the geyser, which fell off the roof onto my car. There is extensive damage to my vehicle & at the time, JnT promised to pay for all repairs to my vehicle that were incurred due to their negligence. However, once I had sent them 3 different quotes from assessors, they stopped taking my calls & eventually offered to give me R2 500.00 for the damages despite the quotes ranging from R5 675.00 to R17,116.36. They also sent an assessor of their choice to do a quote, which they have never sent to me. Clearly the quotes for the repairs were more than they were prepared to pay, despite promising & assuring both my neighbour & I that they would cover all costs. I now have to issue a summons to claim in court. When I phoned their office today, they refused to give me their postal address & told me \I can't just phone & ask for that information". Shocking"