doubled my quote just because of insurance

I spoke with Zandile from the Alberton branch, she gave me a quote of R2380 over the phone for a windscreen<br> <br> then when she sent to insurance the quote doubled .<br> I called her and asked her why, she said its because its insurance that's why the quote went up to R4385<br> <br> I don't understand and this isn't the first time Alberton did this , look previously I had an issue with them and was forced (because of price) to go to another supplier.