Carreras sell well on
ebay , if you have only just bought it and its too big why not take it back assuming its still in A1 condition and try to get a refund .
I ride a carrea vanquish for work and i can honestly say that although its heavy compared to my nice bike it rides just as nicely as my nicer bike which is a lot lighter , i only really notice the weight on hills but it is loaded down with lights,panniers etc .
What other road bike are you comparing it too BTW so we can have a comparison of what your comparing ?, its hard to quantify what you mean by heavy etc till we know what your comparing it too ?
Are there other issues with the bike that might be easy to fix like your seat height / reach etc ( bike fit ) as every bike i buy i expect to change stem length to get it perfect , we cant help if all we have to go on is "its heavy and crank "