Sub-standard Contractors and Unwilling to rectify

My property was affected by the storms in Gauteng on the 9th October 2017. Roof damage was one of the issues. By the 13th October, I still had not received communication from the contractor to come repair. I called in only to be told to get my own quote. Within an hour of receiving my contractors quote, another bank contractor was appointed and in contact. The repair job was completely unsatisfactory and sub-standard. I called back in on the 19th October to request an assessor to come inspect the repair job. He agreed with me and requested a roofing contractor report and quote also, who agreed it was sub-standard work. On the 6th November a get a settlement letter from the bank want to make it my problem and settling my contractors original quote who has not seen the roof since the bank’s repair job. I am requesting the bank to use the roofing contractor that is on their panel to come and repair the roof properly before we have additional damage from more rain.