Should I write letter of dissatisfaction to my insurers or to the garage?

[BroccoliSpears]

Bashed car. Insurance job. Insurers choose which garage I have to use to mend it, therefore not my usual garage.

Garage has been CRAP! Won't bore you with the details. Really pissed off with the whole thing. STILL haven't got my car back.

Should I write to the garage or the insurers? Or both?

both.

as in I would write it to garage but send copy with attached note to the insurers.

I'd contact the garage first and give them the opportunity to resolve it.

Is it the length of time it's taking that's the issue?