Right assuming the person who hit you is insured, you will be claiming off him for the damage to the golf, not sure who you claim off for the disco? There is only your insurance who can write off the golf, the corsa boys insurance cannot.
You can insist the car goes to a vw main dealer for repair and dont accept it back until you are happy with the repairs, even if it costs tens of thousands. They will try to persuade you otherwise but do not resist. You must request a curtisy car from them and any expenses you may incur, through not having the vehicle to hand.
I would check whose insurance is liable for the disco as that could be down to the insurance you have on the golf, Do not get them involved as they could then cut a deal with the corsa insurance to write the golf off