You can just replace the front, however would be concerned with the state of the rear rim, as this probably be in a similar state to the front which failed, feel the braking surface, if this feels concave, it is on it's way out.

You haven't put where you are located, or how much you carry on the bike, but 55kg is light weight so you don't need a real heavy duty setup
If you are doing 100 miles a week, then 4 years is good going for a set of wheels.

For replacements, you are more limited in choice with Campagnolo than Shimano due to the different cassette hub. you have the choice of either pre built Factory wheel, Fulcrum 7's are a good choice here being cheap and durable + good performance, another set of Vento's, or get a pair built on Campagnolo mid range hubs (ike Centaur or Athena) on say Mavic Open Pro rims.