[oemdenied]

Unless the car has been maintained by a Ford dealer and it is still in warranty, which is wont be. I highly doubt Ford will contribute to your engine.
Belt replacement time is dictated by km and time.
Reving the engine over 4k has nothing to do with the failure. The 1.6 duratec is a high reving engine that makes all of its power high up in the rev range. The 1.7 FRP variant makes peak power at 7000rpm with a rev limit of 7200rpm.
Lots of factors could have contributed to the failure such as oil leaking onto the belt, a foreign object fallen in past the cover etc.
Your cheapest option will probably be to source a 2nd hand engine and have it fitted - replace water pump and cambelt BEFORE install at the very least.