How else would you interpret it?
But both phone-calls did happen,,as cars were sent from different directions/locations,arriving within minutes of each other,,so no argument as far as I'm concerned. If Jeremy hadn't had such a weak defence at the time,,then that part of the case could have been solved.
If it had been said that it was one or the other,,then I'd have looked beyond Sheila and Jeremy,,not tossed a coin.