Vodacom fibre never worked from installation date

Vodacom fibre never worked from installation date . After numerous calls to support and technicans coming out my issue was not resolved. I have now cancelled my contract and was told i have to pay R18000 rands for the entire contract. I am not going to pay this because the service was not working from day 1 and it's only 2 months since install. I called alot of times I and send pictures. If the internet never worked from installation why am i been charged R18000. This is very unfair. I how someone from Vodacom sorts this out as i am not paying this bill.