Need to upgrade fan to tow with Audi A5?

I have recently bought an A5 and am getting confusing messages about need for a 'twin fan'. Dealers and Audi UK give equivocal answers. Car handbook is ambiguous. I have towed extensively in past with A4s with no modifications and no problems including over Alps many times in July. Happy to get new fan if necessary but don't want to waste money. Can anyone help? Many thanks.