Payment

I took my car to a shop to find out what was wrong, it was the alternator the shop owner submitted a claim on my 2000 VW Beetle, it was going to cost 485.00 The insurance company only wanted to pay 281.00 my deductible is 100.00 plus the remainder after the 281.00 is paid by this company .I want to know what I'm paying for, what I thought paying was a insurance that picks up the bill, well atleast I thought, but it is so not true.