Hi,
Your garage should not have made you a quotation or told you 'to keep an eye on it'.
On my mk1 Aygo, the water pump started to leak very early. One day, I brought my car for regular servicing and I was asked to schedule a day rapidly to have the water pump changed. It was replaced under warranty.
Your situation is usual with car dealerships. As long as the car is under warranty, there is nothing to worry about, it can wait. And as soon as the warranty has expired, everything needs replacing urgently 😄