This happened us in March in the Caribbean on Arvia. We were sitting up front next to the driver in one of the very small, cramped and run-down buses the islands use. Our guide was also the driver and, at some point early on, he took a call and then balanced the phone on his lap while he steered, constantly looking at it while steering with only one hand, sometimes at speed, and around tricky corners on hillsides. He also spent a great deal of time fiddling about with various things by his side, including a large drinks container, which I eventually offered to hold so it didn't fall over and distract him further. He was a nice guy, but it was unnerving and, if it hadn't been for the fact I was suffering from a virus picked up in the first few days, I would have complained - we did complain about another trip in an open sided safari bus, where we couldn't hear any commentary from the driver/guide for most of the tour, as the speaker bust. He wasn't interested, but we did get a small amount of compensation, and the satisfaction that the problem had been verified and corrected so no-one else missed out knowing where they were going and what they were seeing.
There were LOTS of problems with ship's tours on that particular cruise, including one that we witnessed, where a large number of people crowded around the excursions desk and were shouting very loudly. P&O charges a lot of money for its excursions, and it is their responsibility to make sure people get what they pay for but, most importantly, that they are not exposed to any danger on the roads.
You should complain to them.