I would find a new repair shop, and have them check it. A fuse should not be replaced with a higher amperage one simply because it keeps blowing.
A set of gauges need to be put on it and see if there is enough refrigerant in the system.
Does the compressor come on? There are low pressure switches that won't allow the compressor to come on if the pressure is too low.
Are the fan relays working properly? etc.
Lots of different components that could be the culprit, but with out proper diagnosis you'll just be guessing.