2015 VESPA GTS 300 Engine Problems

MY VESPA GTS SUPER 300CC HAS 2600 MILES AND THE WATER PUMP HAS FAILED. I BOUGHT IT USED AT SCUDERIA IN SAN FRANCISCO. THEY KNEW THIS SCOOTER HAD A BAD WATER PUMP BUT DID NOT DISCLOSE IT BECAUSE IT HAD ALREADY LEAKED ONTO THE MUFFLER PIPE AS CLEARLY SHOWN IN A PIC ON THE AD ON THEIR WEB SITE. I DID NOT KNOW WHAT THAT STAIN WAS UNTIL AFTER I BOUGHT IT AND PUT 200 MILES ON IT. I TOOK IT IN FOR A DIAGNOSTIC AFTER I COMPLAINED ABOUT THE STENCH FROM THE COOLANT ATOMIZING ON THE HOT MUFFLER PIPE IMMEDIATELY AND THEY REITERATED IT'S COMING FROM THE WEEP HOLE. IT'S NOT - AFTER RESEARCHING THE PROBLEM. THEY ARE REFUSING TO FIX IT UNLESS I PAY THEM A $1000+ FOR THE JOB. INITIALLY, THEY HAD OFFERED ME A CONTRACT WITH AEGIS WHICH I REFUSED BECAUSE HE STATED THE SHOP HAD...