All insurance companies have a rule of deduction even if the vehicle is carrying comprehensive insurance. The deduction amount varies from company to company and may also depend on the model of the vehicle. In some companies it is a fixed amount irrespective of the cost of damages or cost of repairs. If the cost of repairing your vehicle is going to be high, then it is better to get it repaired through the insurance and you bear the 30% of the cost. However, if the damages are minor, then I suggest you get the repairs done yourself and not through the insurance company. You should have clarified this deduction at the time of buying the insurance cover and could have insured your vehicle with a company giving better returns for your money.