I had this same issue. But, as I recall, I looked up the solution online pretty quickly, so I didn't waste too much time with it.
Yeah, there was a "easy" fix by buying the tow truck business and doing a tow truck mission, the thing was that I bought that first and I've done all the tow truck missions before the Taxi purchase, that locked me out of that fix... I had to try other fixes that didn't work as promised, but I end up doing something that did trigger the call. It did take some precious time though...
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