The receptionist in the hotel agreed to try to get the hire car people on the phone. Which after an hour of trying she managed.
I kind of forced the company into sending someone down to get the car fixed, they wouldn't send a spare car despite that promise being made on their website. I guess we were lucky that we didn't really have to go anywhere for a few days, so we could let the car hire company come and take it away for repairs and new tyres.
I cannot recommend the car hire company, despite their friendliness. You shouldn't be able to hire an unroadworthy vehicles anywhere in the world.
But they did fix the power steering and put 2 brand new tyres on the car, leaving us with 2 dodgy ones and a barely legal spare. At least this was better than what we had.