Be careful of companies that offer cheap preimums, they will fix your car with second hand parts. On top of that your repair quote will be put online and every dodgy shop on your insurers repair list will bid for the job. If i havent spelt it out enough, your car will be repaired as cheaply as possible.
On the other hand, another insurance company, like shannons, will charge you a more expensive premium BUT you will get the choice of repairer! Your car will also be repaired with new parts, you are also more likely to get a realistic value for you car if its had alot spent on it.
For example with a cheaper premium company, they will only do basically what a stock one is worth, say 18k. With someone like shannons they will do you for say 25k, this is cruicial once you take into account the excess and so on that you will need to minus from what your car is insured for should it be written off.