It something doesn't sound right if the shop "tested" the bulb socket and bulb for the front turn signal is good and it still doesn't light up. Are you sure it's getting power?

If you have a test light, see If you have power up to the back of the housing. If you do then there's somethin wrong inside the headlamp housing (broken wire, burnt bulb, or bulb holder isn't in/contacting correctly).

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